Stephen Hillenburg died of complications from amyotrophic lateral sclerosis, or ALS, at his home in Southern California on Monday. He was diagnosed with the neurodegenerative disease in March 2017.

Nickelodeon shared the unfortunate news via the company's Twitter account. They said, "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."

Hillenburg, who also wrote and directed another Nickelodeon classic 'Rugrats,' saw his first episode of 'Spongebob Squarepants' air in 1999. The show proved to be a huge animation hit, mostly down to his ever-optimistic character Spongebob, and trusty sidekick Patrick the starfish. The series also spawned two movies, countless memes, and even a Tony-winning broadway musical.

Here are some of the tributes to Hillenburg that people have been sharing online.

And finally, David Hasslehoff, the star of 2004's 'Spongebob The Movie' paid tribute to Hillenburg.