Stephen Hillenburg

LOS ANGELES — Stephen Hillenburg, who used his dual loves of drawing and marine biology to spawn the absurd undersea world of “SpongeBob Square-Pants,” has died, Nickelodeon announced Tuesday.

Hillenburg died Monday of Lou Gehrig’s disease, also known as ALS, the cable network said. He was 57. He had announced he had the disease in March 2017. His death comes just weeks after the passing of Marvel creator Stan Lee.

Hillenburg conceived, wrote, produced and directed the animated series that began in 1999 and bloomed into hundreds of episodes, movies and a Broadway show.

The eternally, obliviously jolly SpongeBob and his yell-along theme song that opened “Who lives in a pineapple under the sea?!” quickly appealed to college kids and parents as much as it did kids.

“The essence of the show is that SpongeBob is an innocent in a world of jaded characters,” Hillenburg told The Associated Press in 2001. “The rest is absurd packaging.”

Born at an Army post in Lawton, Okla., Hillenburg graduated from Humboldt State University in California in 1984 with a degree in natural resource planning with a marine emphasis, and went on to teach marine biology at the Orange County Marine Institute.

While there he drew a comic, “The Intertidal Zone,” that he used as a teaching tool. It featured ocean creatures that were precursors to the characters on “SpongeBob.”

He worked on the Nickelodeon show “Rocko’s Modern Life,” from 1993 to 1996 before he began to build SpongeBob’s universe.