Stephen Hillenburg, the creator of Nickelodeon’s signature cartoon series SpongeBob SquarePants, died on Monday. He was 57.

The animator and former marine biology instructor created a powerhouse property with the quirky SpongeBob SquarePants — the global merchandise sales alone have gone north of $13 billion for a brand that has also yielded two animated feature films — with a third due in 2020 — nine music albums, a video game and a Tony-winning Broadway musical.

Hillenburg revealed in March 2017 that he was battling the neurodegenerative disease ALS, or Lou Gehrig’s disease. His death was announced today in a Nickelodeon statement that framed his singular sensibility, which gave the world a loopy but lovable classic of television animation.

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“We are incredibly saddened by the news that Steve Hillenburg has passed away following a battle with ALS,” the network said Tuesday. “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.”

💛 We are sad to share the news of the passing of Stephen Hillenburg, the creator of SpongeBob SquarePants. Today, we are observing a moment of silence to honor his life and work. 💛 — Nickelodeon (@Nickelodeon) November 27, 2018

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With 242 episodes to date, SpongeBob SquarePants has aired in 200 countries and been translated into 50 languages. Last year, at the 45th annual Annie Awards, Hillenburg was presented with the Winsor McCay Award recognizing his career achievements and “exceptional contributions” to animation.

Hillenburg had nine Emmy nominations but never had won the award. That changed in February when he was presented with a special Emmy recognizing his “contribution and impact made in the animation field and within the broadcast industry.” The award was presented by Tom Kenny, the voice of SpongeBob.

Born in 1961, Hillenburg started life in dusty, land-locked Oklahoma, but he would be raised in Southern California, where he found two childhood passions that would shape his future: art and the ocean. His youth in Anaheim also put him in the shadow of Disneyland, an empire built on animation that was infused with optimism.

In 1984, Hillenburg was fresh from graduation at Humboldt State University, where he majored in marine sciences and minored in art. Hillenburg used both disciplines after he landed his first job as a marine biology educator at the Orange County Marine Institute in Dana Point. To keep the young students engaged, Hillenburg wrote and drew The Intertidal Zone, a science lesson in comic book form.

Hillenburg’s efforts to find a publisher for The Intertidal Zone fizzled, but the failed comic book about the briny denizens of a tide-pool would become the early foundation of Bikini Bottom, the vivid community that SpongeBob SquarePants shares with salt-water citizens including Squidward, Patrick, Sandy, Mr. Krabs and Plankton.

Hillenburg enrolled at the California Institute of the Arts in 1987 to pursue a career in animation. He graduated in 1992 with a degree in experimental animation and — thanks to two eye-catching 1992 short films, The Green Beret and Wormholes — got a job at Nickelodeon, where he would work on Rocko’s Modern Life and Rugrats.

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His next success made history. SpongeBob SquarePants premiered in May 1999 and by its second season it was a runaway hit with youngsters as well as cult sensation with college-aged audiences. Hillenburg was the showrunner and executive producer from 1999-2004. The show took a hiatus in 2002 so the SpongeBob team could turn their attention to an ambitious undertaking — transplanting the SpongeBob brand to movie theaters.

The highest-rated show in Nickelodeon’s history made the jump to the big screen in 2004 with The SpongeBob SquarePants Movie, the Paramount Pictures release that made $140 million in worldwide box office.

Hillenburg had envisioned the film (which he produced and directed) as the swan song for Bikini Bottom, a big-screen finale that would save the show from “jumping the shark,” as he put it. The Nickelodeon appetite for the brand was too strong to let it be left on a shelf, however, so Hillenburg decided it was time to leave his animated eco-system in the hands of others.

“It reached a point where I felt I’d contributed a lot and said what I wanted to say,” Hillenburg later explained to the Washington Post. At that point, the show needed new blood, and so I selected Paul [Tibbitt] to produce. I totally trusted him. I always enjoyed the way he captured the SpongeBob character’s sense of humor. And as a writer, you have to move on.”

The Nickelodeon flagship continued to sail on, too, winning over a new generation of fans. That led to a Paramount sequel in 2015, The SpongeBob Movie: Sponge Out of Water, which pulled in $325 million in global box office. More is on the way: The SpongeBob Movie: It’s a Wonderful Sponge is due in theaters on July 17, 2020.

Last year, the sunny and soggy charm of Bikini Bottom took the brand to yet another medium with the premiere of SpongeBob SquarePants: The Broadway Musical.