You have probably heard of SpongeBob, but you may not have known the extent of his popularity.

On opening night, Oct. 7, at Civic Theatre of Allentown’s Nineteenth Street Theatre, the main characters in “The SpongeBob Musical” received thunderous applause when they walked onstage.

It seems that “SpongeBob SquarePants,” the Nickelodeon cartoon series (1999 - present), has worked its way deep into our culture.

The musical is a colorful and fast-moving celebration of the world’s most famous sponge. It should be enjoyed by all children, as long as they are willing to stay in their seats for 2 1/2 hours.

SpongeBob SquarePants (Patrick Mertz) is a fry cook who has ambitions of becoming a manager at the Krusty Krab. The owner Eugene Krabs (JoeMicheal Luciano Zaragoza) dismisses the idea, saying (and singing) that he is just a “simple sponge.”

SpongeBob gets to prove himself, however, when the residents of Bikini Bottom are threatened by a volcano eruption from Mount Humongous.

SpongeBob and his friends, Sandy Cheeks (Miki Fuentes) and Patrick Star (Andrew Mark Schaffer), have to climb the mountain to save the town. Patrick is distracted when he becomes the leader of a cult of sardines.

There is a dastardly villain, Sheldon Plankton (Doug Ace), who is trying to regain the love of his girlfriend Karen the Computer (Grace Nyberg). They are trying to upset SpongeBob’s quest.

Meanwhile, Squidward Q. Tentacles (Jaedon R. Muhl) is setting up a concert with the Electric Skates, even though he would rather perform himself. Eugene’s daughter, Pearl Krabs (Janaya Morgan), is a wanna-be a backup singer with the group.

If this seems a bit confusing, never fear. It all makes sense once you are immersed in the world of Bikini Bottom. It starts with a Prologue, when Patchy the Pirate (Shaun Hayes) paces the stage and speaks before guards take him away (He also sings “Poor Pirates” before Act II).

You can see sea creatures moving behind the curtain. The stage is framed by strips of neon that change the color overlaying the action. Many times there are more than 20 people on stage, sometimes more than 30, with many costume changes among the cast.

Being aimed at youths, the musical numbers emphasize self-determination. SpongeBob and Squidward sing about alienation with “(Just A) Simple Sponge” and “I’m Not A Loser,” and about ordinary beings stepping up to challenges with “Hero Is My Middle Name.”

Despite contributions by David Bowie, Cyndi Lauper, John Legend, Steven Tyler, and Joe Perry, there are no standout songs. But the cast delivers them wonderfully.

Mertz captures SpongeBob’s relentless optimism with a voice that is impressively powerful coming from a sponge. Fuentes and Morgan also contribute vocals that seem capable of causing an eruption just from their singing.

Schaffer is appealingly mentally-dense, Muhl is a sympathetic loser, Ace is sneaky, and Zaragoza is gleefully greedy.

“The SpongeBob Musical,” directed by William Sanders, is a must-see for fans of the Nickelodeon show, and can be recommended even to those rare children (and parents) who have never heard of him.

“The SpongeBob Musical” continues 7:30 p.m. Oct. 14, 15, 20, 21, 22; 2 p.m. October 16, 23, Civic Theatre of Allentown, Nineteenth Street Theatre, 527 19th St. Allentown. Tickets: https://civictheatre.com/ ; 610-433-8903