The Intertidal Zone

While working at the Ocean Institute, Hillenburg wrote a comic book entitled The Intertidal Zone, which he used to teach his students about the animal life of tidal pools.<ref>Template:Cite webTemplate:Subscription required</ref> The comic starred various anthropomorphic forms of sea life, many of which would evolve into SpongeBob SquarePants characters,<ref name="Banks, p. 9">Template:Harvnb</ref> including "Bob the Sponge", who was the co-host of the comic and resembled an actual sponge, as opposed to SpongeBob SquarePants who resembles a kitchen sponge.<ref name="Origin of SpongeBob SquarePants">Template:Cite AV media</ref> Hillenburg tried to get the comic professionally published, but was turned down by the publishers he approached.<ref name="HillenburgInt" />