Groot quickly became a fan favorite after his cinematic debut in Marvel's "Guardians of the Galaxy" back in 2014, but the version audiences came to know and love almost looked quite a bit different than the bark-covered giant seen in the film.

A Senior Illustrator for Marvel Studios, Jackson Sze, posted an early piece of Groot concept art on Instagram that gives the monosyllabic muscleman -- muscleplant? -- a layer of green moss.

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Sze says he tried out this variation to "soften his look," and that the idea was eventually integrated into the final version that made it to film.

Check out Sze's mossy Groot concept art below:

Early portrait of #groot where I tried to soften his look by covering his face with mosses. The idea was integrated into the final design by @droidsforsale #GOTG #marvelstudios #conceptart A photo posted by Jackson Sze (@jwsze) on

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Voiced by Vin Diesel in the movie, Groot is a sentient plant-like creature whose vocabulary is constricted to variations on the phrase "I am Groot." Created by Stan Lee, Jack Kirby and Dick Ayers, Groot first appeared way back in 1960 as a villainous alien invader, before being reintroduced in 2006 as a much more well-meaning member of the Guardians. The last we saw of him, Groot had reborn as a much smaller version. Director James Gunn recently revealed that Groot would be toddler-sized for at least some portion of the much-hyped "Guardians of the Galaxy 2," which is set to hit theaters on May 5, 2017.