The creator of Nickelodeon’s “SpongeBob SquarePants,” Stephen Hillenburg, has died at age 57.

Variety reported that the cause of death was ALS, or amyotrophic lateral sclerosis, also called Lou Gehrig's disease. Hillenburg announced he was diagnosed with the disease in March.

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"We are incredibly saddened by the news that Steve Hillenburg has passed away following a battle with ALS," Nickelodeon said in a statement, according to Deadline. "He was a beloved friend and long-time creative partner to everyone at Nickelodeon, and our hearts go out to his entire family. Steve imbued 'SpongeBob SquarePants' with a unique sense of humor and innocence that has brought joy to generations of kids and families everywhere. His utterly original characters and the world of Bikini Bottom will long stand as a reminder of the value of optimism, friendship and the limitless power of imagination."

According to The Hollywood Reporter, Hillenburg graduated from Humboldt State University in 1984 with a bachelor's degree in Natural Resource Planning and Interpretation, with an emphasis on marine resources. Variety reported that he taught marine biology at the Orange County Marine Institute (now the Ocean Institute) in Dana Point, California, later taking his talent in writing and illustration and love of the sea to create "SpongeBob SquarePants."

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First airing on Nickelodeon on May 1, 1999, more than 250 episodes of the cartoon series have aired to date. Hillenburg left the show after its third season to write, direct and produce “The SpongeBob SquarePants Movie,” which was released in 2004 and grossed $140 million globally. Hillenburg returned to the show in 2015 as an executive producer, also taking on that role for 2015’s “The SpongeBob Movie: Sponge Out of Water.”

Hillenburg is survived by his wife of 20 years, Karen Hillenburg; son Clay; mother Nancy Hillenburg; brother Brian Kelly Hillenburg and his wife Isabel and nieces Emma and Hazel.