It’s a sad day for Nickelodeon and cartoon fans everywhere.

“SpongeBob SquarePants” creator Stephen Hillenburg has died at age 57.

On Twitter, Nickelodeon says Hillenburg died Monday of Lou Gehrig’s disease, also known as ALS.

Hillenburg created, wrote, produced and directed the animated series SpongeBob Sqaurepants.

Here you can watch an interview with Stephen Hillenburg as he shares his interest in Marine Biology and how it eventually led him to create SpongeBob SquarePants.

The show starting broadcasting in 1999 and has since became a worldwide phenomenon spawning hundreds of shows.

He is survived by his wife, Karen, and son, Clay.