Stephen Hillenburg, a graduate of CalArts and creator of the award-winning and widely popular cartoon series, “SpongeBob SquarePants,” died Monday. He was 57.

According to Variety online, Hillenburg was diagnosed with ALS (also known as Lou Gehrig’s disease) in March of last year.

“We are sad to share the news of the passing of Stephen Hillenburg, the creator of ‘SpongeBob SquarePants,’” Nickelodeon tweeted Tuesday. “Today, we are observing a moment of silence to honor his life and work.”

Hillenburg was born on Aug. 21, 1961, at Fort Sill in Lawton, Oklahoma. He taught Marine Biology at what is now Orange County Ocean Institute in the 1980s. In 1987, he decided to pursue his second lifelong passion – animation. He earned a Master of Fine Arts in experimental animation degree from the California Institute of the Arts in 1992.

Hillenburg wrote a comic book called “The Intertidal Zone” during his time at the Ocean Institute. He showed it to a friend, who was also one of the writers on “Rocko’s Modern Life.” His friend, Martin Olson, suggested Hillenburg rewrite it as an undersea cartoon series. Hillenburg then pitched the idea to Nickelodeon in 1998. Nickelodeon bought the pitch and in July 1999, “SpongeBob SquarePants” premiered.

For more on the life of Stephen Hillenburg, click [here].

Hillenburg is survived by his wife Karen and son Clay.