The very first Teenage Mutant Ninja Turtles drawing, thrown together as a joke in November 1983 by Kevin Eastman and Peter Laird, was bought Friday by an anonymous bidder for $71,700 at Heritage Auctions in Dallas. An undisclosed percentage of the proceeds will be donated to The Hero Initiative.

“What an incredibly exciting week this has been! The Turtles have been blessed with the best fans on the planet, so I chose this event to make available personal historical TMNT items for those really hardcore supporters – but WHOA – what a response!” Eastman, who consigned  the sketch to the auction house, wrote in a statement. “My many, many, thanks to all the fans that have given me the best job in the world, and for their love for a great, goofy, bunch of green guys that just wanted to be normal teenagers – Mutant Ninja ones anyway!”

That 1983 drawing led the following year to the publication of Teenage Mutant Ninja Turtles #1, a black-and-white parody from Eastman and Laird's Mirage Studios, that, with the help of licensing agent Mark Freedman, grew into a multimedia empire of comics, animated television series, feature films, video games and merchandise. Laird completed a buyout of Eastman's interests in TMNT in 2008, and then sold the property to Viacom the following year for $60 million.

"For 30 years the Turtles have been a worldwide phenomenon, entertaining hundreds of millions of children and that influence shows no sign of slowing with the upcoming TV and film projects featuring the team," Barry Sandoval of Heritage Auctions said of the sketch. "This is a piece of pop culture that will only increase in value and influence over the coming decades.”