Over the last 18 years, SpongeBob SquarePants and his friends in the underwater town of Bikini Bottom have been a pop culture juggernaut — a long-running TV show, a movie franchise, tons of tie-ins. And now SpongeBob is making his mark on the Broadway stage.  Click the audio player above to hear the full story. 

The cartoon character is a huge cash cow for Nickelodeon, but are there signs that SpongeBob is falling out of favor with kids?