"Very sad to hear the news of the passing of Stephen Hillenberg (sic), who years and years ago used to be my neighbor and kindly did the artwork for the first music that I ever released," the musician wrote on Instagram. "The photo from the Record was shot behind his apartment. Better known as the creator of SpongeBob SquarePants, I always remembered him as a genuinely sweet guy. I was lucky to get to run into him by chance at the airport a few months ago. Sending my condolences to his family and to all the friends who are missing him today and thinking about old times." ALSO: SpongeBob fans recall their favorite episodes.