In this Jan. 31, 2015 file photo, SpongeBob SquarePants creator Stephen Hillenburg attends the world premiere of "The SpongeBob Movie: Sponge Out Of Water" in New York. Hillenburg died Monday, Nov. 26, 2018 of ALS. He was 57. Credit: Charles Sykes | Invision/AP

Stephen Hillenburg, the animator whose childhood summers on a Maine island later inspired him to create “SpongeBob Squarepants,” died Monday in California at the age of 57, according to Nickelodeon, the network that runs the show.

The cause of death was ALS, also known as Lou Gehrig’s disease, a progressive neurodegenerative disorder, according to media reports. Hillenburg revealed his ALS diagnosis in March 2017.

Raised in California, Hillenburg spent summers earlier in his life on Islesford, an island off of Mount Desert Island that is accessible only by boat.

Hillenburg credited his time on the island — the approximate population of which varies from 100 to 400, depending on the time of year — with helping to inspire the ideas and characters that later developed into the multibillion dollar cartoon franchise that has run on Nickelodeon since its inception in 1999.

AdAge reported in 2009, on the occasion of the 10th anniversary of the show, that SpongeBob retail merchandise licensed by Nickelodeon generated nearly $8 billion a year in revenue for the network.

For a few summers after high school, Hillenburg worked as a fry cook and lobster boiler at the Islesford Dock restaurant. He told a California court in 2008 that the experience “later became the inspiration for the job held by [SpongeBob], who is the fry cook at the ‘Krusty Krab’ fast food restaurant [in the series].”

Hillenburg provided the information after he and Nickelodeon were sued for alleged copyright infringement by another cartoonist who claimed he had invented the SpongeBob character in 1991. The judge subsequently rejected the rival cartoonist’s claims and ruled in favor of Hillenburg and Nickelodeon.

Hillenburg first got the idea for the character in 1989, when he was working as an instructor and staff artist at Orange County Marine Institute, as part of an educational comic he created that featured talking sea creatures.

Five years later, after he had switched careers and was working for Nickelodeon on another animated show, Hillenburg revisited the concept and further developed the character now known as SpongeBob.

“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. “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.”

The absurdly jolly SpongeBob, his starfish sidekick Patrick, and a vast cast of oceanic creatures 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.”

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. He 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. Its nearly 250 episodes have won four Emmys and 15 Kids Choice Awards, and led to an endless line of merchandise to rival any other pop cultural phenomenon of the 2000s.

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.”

A musical stage adaptation bowed 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.

The Associated Press contributed to this report.

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....