 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 . 
