Stephen Hillenburg, the creator/animator of Nickelodeon’s animated hit series “SpongeBob SquarePants” has died. He was 57.

Hillenburg revealed last year that he was battling ALS — amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease, a progressive neurodegenerative disease affecting nerve cells in the brain and the spinal cord.

Nickelodeon on Tuesday announced “a moment of silence” via Twitter in honor of Hillenburg.

In a written statement, the network said: “We are incredibly saddened by the news that Steve Hillenburg has passed away following a battle with ALS. He was a beloved friend and longtime 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.”

On the big screen, Hillenburg wrote, produced and directed the 2004 feature film “The SpongeBob SquarePants Movie,” which spawned the 2015 sequel, “The SpongeBob Movie: Sponge Out of Water.”

With an appeal to children and adults, the TV series, centered around the denizens of an underwater world known as Bikini Bottom, began airing in 1999 and has aired nearly 250 episodes. The series has won four Emmy Awards.

A stage musical based on the hit series and featuring the music of Steven Tyler, Sara Bareilles, Cyndi Lauper and John Legend, among others, had its pre-Broadway world premiere in Chicago in 2016. The musical would go on to earn 12 Tony Award nominations.

The absurdly 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 fact that it’s undersea and isolated from our world helps the characters maintain their own culture,” Hillenburg told The Associated Press in 2001. “The essence of the show is that SpongeBob is an innocent in a world of jaded characters. The rest is absurd packaging.”

Its vast cast of oceanic creatures included SpongeBob’s starfish sidekick Patrick, his tightwad boss Mr. Krabs, squirrel pal Sandy Cheeks and always-exasperated neighbor Squidward Tentacles.

“SpongeBob SquarePants” the stage musical received 12 Tony Award nominations. | Joan Marcus/Boneau/Bryan-Brown, via AP

While Hillenburg introduced and popularized exotic creatures like the sea sponge, Bikini Bottom was a realm like no other, real or fictional. SpongeBob (voiced by Tom Kenny) can play his nose like a flute and could not possibly be happier to work his fast-seafood job of flipping Krabby Patties.

Born at his father’s army post in Lawton, Oklahoma, Hillenburg graduated from Humboldt State University in California in 1984 with a degree in natural resource planning with an emphasis on marine resources, 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 anthropomorphic ocean creatures that were precursors to the characters on “SpongeBob.”

Hillenburg shifted to drawing and earned a master of fine arts degree in animation from the California Institute of the Arts in 1992.

That same year he created an animated short called “Wormholes” that won festival plaudits and helped land him a job on the Nickelodeon show “Rocko’s Modern Life,” where he worked from 1993 to 1996 before he began to build SpongeBob’s undersea world of Bikini Bottom, which showed off his knowledge of marine life and willingness to throw all the details out the window.

“We know that fish don’t walk,” he told the AP, “and that there is no organized community with roads, where cars are really boats. And if you know much about sponges, you know that living sponges aren’t square.”

The show was an immediate hit that has lost no momentum in the nearly 20 years since its creation. It became one of the biggest pop culture phenomena of the 2000s.

“When you set out to do a show about a sponge, you can’t anticipate this kind of craze,” Hillenburg told the AP in 2002.

Intensely involved in every aspect of the show initially, Hillenburg after the 2004 film stepped back into an executive producer role on the show, where he remained for the rest of his life.

Hillenburg is survived by his wife of 20 years Karen Hillenburg, son Clay, mother Nancy Hillenburg, and a brother, Brian Kelly Hillenburg.

Contributing: Associated Press