 While Hillenburg was there, he created a precursor to SpongeBob SquarePants: a comic book titled The Intertidal Zone, which was used by the institute to teach visiting students about the animal life of tide pools. The comic starred various anthropomorphic sea lifeforms, many of which would evolve into SpongeBob characters. Hillenburg tried to get the comic professionally published, but none of the companies to which he sent it were interested.
