Is Steven Universe the best cartoon on TV? Yeah, that seems like a fair assessment. The Simpsons and Adventure Time have had higher highs, but much lower lows, and Adventure Time is ending soon anyway. Rick and Morty is funnier but has less heart, Bojack Horseman has heart but less impressive animation and no other American cartoon even comes close, so yeah. Saying it here: Steven Universe is the best overall current American cartoon. Not that this is likely to be super controversial. The show has a devoted all-ages following like few others, and even in its fifth season it keeps surprising viewers. Following the history-making "Heart of the Crystal Gems" arc, the launch of the show's partnership with the Dove Self-Esteem Project and the announcement of a movie at San Diego Comic Con, now's a good time to look at Steven Universe in-depth.

The team that makes the show (known by fans as the "Crewniverse") has talked a lot about how the show is made and how it's evolved over time. For the hardcore fan obsessed with knowing all there is to know about the series, the official Steven Universe: Art & Origins book provides a wealth of info, as does Cartoon Network's The Steven Universe Podcast. Not everyone is so hardcore as to spend so much time researching every little detail about Steven Universe, though. For those who haven't taken the deep dive but want to know more, this list will reveal to you 20 fascinating mysteries about Steven Universe you might not have known before.

SPOILERS ahead!

20 MIKE MIGNOLA HELPED BUILD THE MYTHOLOGY

mike mignola

One big lesson aspiring artists can learn from Steven Universe creator Rebecca Sugar: don't be afraid to speak to and even show off to your heroes at conventions. Long before she got into animation, Sugar would regularly talk to Hellboy creator Mike Mignola at conventions and show him her independent comics, which he'd give her advice on.

When she was finally starting work on Steven Universe, Mignola's expertise in mythology proved very helpful. He particularly suggested she research the Babylonian goddess Ishtar for inspiration. Various aspects of Rose Quartz, from her lions to her use of star imagery for the Crystal Gems, come directly from Ishtar.

19 GENNDY TARTAKOVSKY WORKED ON THE PILOT

steven universe pilot

Around the same time she started developing Steven Universe, Rebecca Sugar did some storyboards for Hotel Transylvania. Between that and her Marceline-heavy episodes of Adventure Time, she must really like drawing vampires! Genndy Tartakovsky, the director of Hotel Transylvania and creator of Dexter's Lab and Samurai Jack, provided constructive feedback on her early Steven Universe ideas.

Genndy actually directed the animation for the show's pilot! He didn't work on the show itself, and the look of the pilot is extremely different from the final show, but his influence is still felt. If anything, the more streamlined final designs are closer to Genndy's typical style than the pilot designs were.

18 THE GEMS ARE NONBINARY WOMEN (LIKE REBECCA SUGAR)

rebecca sugar

The Gems are fairly unusual in animation as an alien race where everyone (half-human Steven excepted) presents feminine and uses "she/her" pronouns. There has been some debate as to whether they should be considered female characters or if they're essentially genderless. Turns out, the answer is... both!

In a recent NPR interview, Rebecca Sugar clarified that the Gems are "nonbinary women." What does that mean? Basically, it means they don't see themselves as women but are fine being seen as women by others. It turns out this comes from a personal place: Rebecca Sugar identifies as a nonbinary woman and is OK being referred to by either "she/her" or "they/them" pronouns.

17 LARS AND SADIE CAME BEFORE THE GEMS

lars sadie steven universe

Two of the most prominent supporting characters actually predate the creation of the main cast of Steven Universe. Lars Barriga and Sadie Miller, the on-again off-again teen couple that used to run the Big Donut (before Lars went to space and Sadie became a rock star), were first created when Rebecca Sugar was in college.

While the characters originally had no connection to anything else relating to Steven Universe, Sugar decided to incorporate them into the show early on, right from the pilot episode. It seems she has a personal connection with them; Sadie's rock band is based on the one Sugar was part of in college.

16 PROTO-LAPIS DATED... SONIC THE HEDGEHOG?

margo in bed

One of Rebecca Sugar's early unfinished comic books, Margo in Bed, was supposed to be a response to a troubled relationship and a rough break-up. The couple in this story consisted of Margo, one of Sugar's old self-inserts from high school she's described as a "proto-Lapis," and a character named "Rad Rover."

In the art magazine Frontier #14, Sugar describes Rad Rover as a "composite character" with '90s cartoon influences. The most obvious influence on Rad Rover, between the "xtreme" attitude and that distinctive hair, is clearly Sonic the Hedgehog. Yes, the inspiration for Lapis was in a messed up relationship with what was essentially Sonic the Hedgehog.

15 THE "REAL" STEVEN WORKS ON THE SHOW

rebecca and steven sugar

Rebecca Sugar's main inspiration for the character of Steven Universe is her brother, Steven Sugar. She's said her brother's long been her closest friend and that the Crystal Gems are all based on different aspects of her relationship with him. Steven Sugar didn't just inspire Steven Universe, he also works as a background artist on the show!

Steven both designs and paints much of the show's stunning background art. In addition to Steven Universe, he's also worked on Bravest Warriors, Adventure Time and Ben 10. Currently he's the lead background designer on the upcoming Disney series The Owl House.

14 THE OFF-MODEL ANIMATION IS INTENTIONAL

steven universe off model

One thing you notice when you watch a lot of Steven Universe is that the characters don't always look the same from episode to episode, or even from scene to scene. Some consider all "off-model" animation to be bad, but in Steven Universe, it's intentional. The animators are instructed not to strictly copy model sheets, but rather to adhere to the personal drawing styles of the different storyboarders.

You might like some boarders' styles more than others, but this freedom allows for lots of creativity, expressiveness and cartoony visual humor. Adventure Time, where Rebecca Sugar got her start, had a similar method of production, while former Steven producer Ian Jones-Quartey has pushed "off-model" animation even further in OK K.O.! Let's Be Heroes.

13 RONALDO'S BLOG IS REAL... AND BECAME A BOOK

Ronaldo Steven Universe

One of the most controversial characters on the show, to say the least, Ronaldo Fryman is Beach City's resident conspiracy theorist and otaku. In the show, his attempts to decipher the bizarre goings on in his hometown are posted on a blog titled "Keep Beach City Weird." This blog has actually been de-fictionalized into a tumblr account run by writers Matt Burnett and Ben Levin.

This tumblr provided real time commentary on the events of the show throughout its first three years on the air, all in Ronaldo's semi-observant but often point-missing style. The blog evolved into a book. After the book's publication, Matt and Ben left Steven Universe to create Craig of the Creek, and the blog stopped updating.

12 PERIDOT'S TWITTER IS REAL... BUT HARASSMENT ENDED IT

peridot steven universe

In the episode "Too Short to Ride," Peridot became obsessed with posting social media updates on her new tablet. Like the Keep Beach City Weird blog, Peridot's Twitter was also defictionalized. Storyboard artist Jesse Zuke (then credited as Lauren Zuke) ran the account.

Alas, harassment from fans angry about certain relationships in the show drove Zuke to delete Twitter in August 2016. The Peridot account was only updated once since then, for a single post on May 23, 2017. Zuke has since left the Crewniverse and the animation industry in general, leaving for a variety of reasons -- but the toxic fans certainly didn't help.

11 IAN JQ'S FAMOUS GRANDMA INSPIRED NANEFUA

Nanefua Steven Universe

Nanefua Pizza, the matriarch of the Pizza family, became the new Mayor of Beach City in the season five episode "Dewey Wins." This development was a lot less surprising who knew that Nanefua is actually based on a celebrated stateswoman: Theodosia Okoh, who also happens to be Ian Jones-Quartey's maternal grandmother.

Theodosia Okoh is best known for designing the official flag of Ghana in 1957, when the nation declared independence from Britain. She was also the first female chairman of the Ghana Hockey Association. Ghana's National Hockey Stadium was named after her in 2004. She passed away in 2015 at the age of 92.

10 KOALA PRINCESS IS NOW A CHARACTER IN OK K.O.

koala princess ok ko

"Koala Princess" is a fictional show-within-a-show in the world of Steven Universe, an anime which Ronaldo and his ex-girlfriend bonded over. Details of the show's actual contents were confusing: sometimes she was drawn as an actual koala with a tiara, other times as a human with koala ears. Who is Koala Princess really?

Turns out there's some crossover between Steven Universe's fiction and OK K.O.'s reality. In OK K.O., Koala Princess is a student at the P.O.I.N.T. Prep hero academy with the power to transform herself into a koala (explaining the two different designs). OK K.O. is set to feature more crossovers in the future: an episode titled "Crossover Nexus" will feature Garnet, as well as Ben 10 and Teen Titans Go's Raven!

9 "OCEAN GEM" WAS WRITTEN AS A SERIES FINALE

steven universe lapis ocean gem

Many of the big plot points in Steven Universe, including Garnet's fusion status, Lars' magical transformation, Rose's secret identity and Ruby and Sapphire's wedding, were all there in the original plan for the series. Even so, there was no guarantee the show would last long enough to reach those reveals, and the show almost ended at a much earlier point.

"Ocean Gem," the show's 26th episode, was originally written with the intention of being a possible series finale. It's also the episode many fans point to as the one where the show evolved from merely entertaining to genuinely gripping. Of course, Cartoon Network ordered many more episodes, so the final dialogue in "Ocean Gem" was rewritten to be less conclusive.

8 THE ENDING THEME'S MEANING KEPT CHANGING

steven universe ending background

"Love Like You," the Steven Universe ending theme, was written over the course of three seasons, only heard in full in the season three finale "Bubbled." For season one, it was just instrumental music. Rebecca Sugar added lyrics over seasons two and three, one verse at a time given the briefness of the credits' runtime. Over time, the song's meaning evolved.

At first, the song was about an alien being confused by the love of a human. It's easy to attribute this perspective to the character of Rose Quartz. As the writing process progressed, however, Rebecca Sugar realized it was a more personal song about her own insecurities and desire to be there for the many people, especially her brother Steven, who've supported her.

7 THE CLUSTER WAS ALMOST A LOT SCARIER

Steven Universe cluster

The Cluster was first mentioned as the reason Jasper was checking on Earth in the season one finale "Jail Break." At the time, however, the writers weren't sure what exactly The Cluster was going to be. At one point it was supposed to be a giant monster the Crystal Gems would have to fight, one which this concept art shows would have been pretty terrifying.

It was only midway through production on season two that the Crewniverse figured out the Cluster's less scary-looking but still extremely dangerous form: an experimental weapon made of broken gem shards in the Earth's core. Steven managed to stay calm and safely bubble The Cluster, and when it finally emerged three seasons later in "Reunited," it was on the heroes' side.

6 THE VOICES THAT WERE ALMOST AMETHYST AND GARNET

the new crystal gems

In the episode "The New Crystal Gems," Connie, Peridot, Lapis and Pumpkin fill in as Beach City's protectors while the main characters are away in outer space. Peridot takes on the role of Garnet, Lapis does her best Amethyst, human Connie gets the Steven role de facto and Pumpkin's the new Pearl.

The humor the characters forcing themselves into other's roles is obvious enough, but there's a less obvious in-joke here. You see, Shelby Rabara, the voice of Peridot, auditioned for a bunch of roles and was almost cast as Garnet, while Lapis' VA Jennifer Paz was in the running to play Amethyst.

5 THE KINDERGARTEN REFERENCES A SCARY MANGA

Steven Universe Kindergarten

Steven Universe is filled with anime and manga references. Homages to Revolutionary Girl Utena, Neon Genesis Evangelion, Dragon Ball Z and others abound. The deepest cut otaku reference in the show is in the design and introduction of the Kindergarten in "On the Run."

All those person-shaped holes in the walls are inspired by the setting of Junji Ito's short horror manga The Enigma of Amigara Fault. The particular scene in which Amethyst slides into one of the holes screaming "It's my hole! It's me-sized!" comes almost directly from the work of an manga author known for stories much less cute and wholesome than Steven Universe.

4 CHARACTERS AND CREATORS CAMEO IN LITTLE WITCH ACADEMIA

Little Witch Academia Rebecca Sugar Ian JQ

You expect Steven Universe to reference anime, but you might not expect anime to reference Steven Universe! The animators at Studio Trigger, however, are huge Western animation fans, and their Little Witch Academia franchise contains multiple homages. Steven's friend Connie appears in the background in the second OVA, while Rebecca Sugar and Ian Jones Quartey appear in the TV series' finale.

LWA animator Takafumi Hori and Rebecca Sugar's mutual admiration led to one of the most beautiful Steven Universe moments. Hori did the animation for the "Here Comes a Thought" song in the episode "Mindful Education." Hori regularly posts Steven Universe fan-art on social media.

3 THE STEVEN UNIVERSE-MST3K CONNECTION

joel hodgson tom servo crow mst3k

Rebecca Sugar was a Mystery Science Theater 3000 fan for a long time; some of her earliest art online included MST3K slash fan-art! In Steven Universe, original MST3K host Joel Hodgson is the voice of the disgraced mayor turned donut salesman Bill Dewey.

That connection went in the opposite direction when a successful Kickstarter campaign brought MTS3K back from the dead. Both Rebecca and Steven Sugar designed the sets for the new Netflix-based revival. They're not the only Cartoon Network creators to take part: Adventure Time's Pendleton Ward did some special animation, while Rick and Morty's Dan Harmon and Justin Roiland were guest writers.

2 UNCLE GRANDPA KNEW ABOUT PINK DIAMOND

Steven Universe Uncle Grandpa

The twist that Rose Quartz was actually Pink Diamond is one of those mind-blowers that completely re-contextualizes everything that came before it in the series. It certainly adds a new dimension to Pearl's whole character. It also makes Bismuth's story make a lot more sense. Foreshadowing of this twist, however, can be found even in the places you'd least suspect... like the Uncle Grandpa crossover episode!

"Say Uncle" was definitely one of the more controversial episodes, a non-canonical crossover with Cartoon Network's silliest show Uncle Grandpa. However Uncle Grandpa had some good advice for Steven about washing his gem twice a year. Quartz gems don't need to be washed. Diamonds do. Uncle Grandpa knows all!

1 SURVIVING A HATE CRIME INSPIRED "STRONGER THAN YOU"

garnet steven universe

The song "Stronger than You," in which Garnet celebrates her pride in being a fusion while kicking Jasper's tail, is one of the most beloved songs in the series for good reason. The story behind this song is both upsetting and inspiring. In the same interview where she came out as non-binary, Rebecca Sugar also recounted a time in 2009 when a group of skinheads attacked her and Ian Jones-Quartey.

"I wanted to normalize this image of a gender-expansive, interracial couple," she said, "and 'Stronger than You' was very much about the fact that our relationship survived." The way Garnet, the embodiment of a loving relationship between two different types of Gems, triumphs over her enemies is all the more moving knowing her inspiration.