SpongeBob SquarePants is an American animated television series created by marine biologist and animator Stephen Hillenburg that premiered on Nickelodeon on May 1, 1999. The series is set in the fictional underwater city of Bikini Bottom, and centers on the adventures and endeavors of SpongeBob SquarePants, an over-optimistic sea sponge. Many of the ideas for the show originated in an unpublished, educational comic book titled The Intertidal Zone, which Hillenburg created in the mid-1980s. He began developing SpongeBob SquarePants into a television series in 1996 after the cancellation of Rocko's Modern Life, another Nickelodeon television series that Hillenburg previously directed.