Stephen Hillenburg, creator of the absurd undersea world of children’s cartoon favourite SpongeBob Squarepants, has died at the age of 57.

Children’s cable television network, Nickelodeon, confirmed Hillenburg’s death in a statement Wednesday morning.

The former marine biologist died Monday (US time) of Lou Gehrig’s disease, also known as ALS, Nickelodeon said.

Hillenburg announced he had the disease in March 2017. 

Since its debut, the show included hundreds of episodes and spawned movies and a Broadway show.

The absurdly jolly SpongeBob and his theme song that opened with “Who lives in a pineapple under the sea?!” quickly appealed to young adults and parents as much as it did children.

“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,” he said.

The cast of oceanic creatures included SpongeBob’s starfish sidekick Patrick Star, his miserly boss Mr Krabs, squirrel Sandy Cheeks and always-exasperated neighbour Squidward Tentacles.

“He was a beloved friend and long-time creative partner to everyone at Nickelodeon, and our hearts go out to his entire family,” Nickelodeon’s statement said.

“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.”

Born in Lawton, Oklahoma, Hillenburg graduated from Humboldt State University in California in 1984 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 Squarepants.

Hillenburg went on to earn 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.

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

The almost 250 Spongebob episodes earned four Emmy Awards and 15 Kids’ Choice Awards, as well as spawning a massive line of merchandise.

The Spongebob series earned multiple awards. Photo: Getty

“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.

In 2004, the show shifted to the big screen with The SpongeBob SquarePants Movie and a 2015 sequel, The SpongeBob Movie: Sponge Out of Water.

After being initially being intensely involved in every aspect of the show, Hillenburg stepped back into an executive producer role after the 2004 movie, a job he retained for the rest of his life.

A musical stage adaptation debuted on Broadway in 2017, with music from such stars as Steven Tyler, Sara Bareilles and John Legend. It earned 12 Tony Award nominations, including one for best performance by a leading actor for Ethan Slater.

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

-with agencies