Hillenburg died on Monday, November 26, 2018 but his death was announced by Nickelodeon television network on Tuesday, November 27, 2018.

“We are incredibly saddened by the news that Steve Hillenburg has passed away following a battle with ALS. He was a beloved friend and long-time creative partner to everyone at Nickelodeon, and our hearts go out to his entire family,” the network said in a statement.

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In 2017, Hillenburg opened up on his battle with neurodegenerative disease ALS, also known as Lou Gehrig’s disease.

Hillenburg, who was a marine biology teacher in Southern California, created sea creatures as teaching tools.

His teaching tools were made into the zany cartoon marine underworld of Bikini Bottom which kicked off a new wave of cartoon series in television.

The production has also been turned to a series of spin-off books, two Hollywood movies and a Broadway musical.

“SpongeBob SquarePants,” features the cheerful yellow sea sponge, who lived in an underwater pineapple, and his friends Mr. Krabs, Larry the Lobster, Patrick, and their Krusty Krab restaurant hangout.

The first episode of the cartoon series aired on U.S. television in May 1999.