– Aquaman only thinks he’s king of the sea.

That title rightly belongs to SpongeBob SquarePants, whose superpower — an unsinkable spirit — has kept him on the throne for most of two decades.

“He’s the person you want to be with, that’s always looking at things from a positive angle,” said Carolyn Lawrence. She voices the character of Sandy Cheeks on the Nickelodeon series, which celebrates its 20th anniversary with a one-hour special Friday, “SpongeBob’s Big Birthday Blowout” and a party Saturday at the Mall of America.

“Something terrible could be going on and SpongeBob’s going to see the good side of it. That’s a really fun place to be.”

The show may not be as popular as it was in its heyday, when 60 million viewers were tuning in every month, but the characters are still soaking up the love. “SpongeBob SquarePants” remains the top-rated series in kids animation with a TV spinoff in the works and a third feature film slated for 2020.

New toys based on the show’s popular memes are helping to boost merchandise sales past the $13 billion mark. A Broadway musical garnished 12 Tony Award nominations last year. RockBottom Plunge, a roller coaster inspired by an early episode, remains one of the most popular attractions at theMOA’s Nickelodeon Universe.

Maroon 5 nearly salvaged its much-maligned Super Bowl halftime show last winter by having SpongeBob’s pal Squidward Tentacles introduce one of the songs. The band may have won over the critics if they had given the clarinet-blowing octopus a solo.

“People get mad at the NFL. They don’t get mad at SpongeBob,” said Tom Kenny, who has voiced the title character since the beginning. “They don’t hate on SpongeBob. They hate on Maroon 5.”

The series, which debuted on July 17, 1999, was the brainchild of Stephen Hillenburg, a biology instructor. He noticed how children were enraptured by underwater creatures when they visited the Orange County Marine Institute. His concept, which took 10 years to develop, was instrumental in making Nickelodeon a cable powerhouse.

By the third season, “SpongeBob” was TV’s most-watched children’s show, a title it has yet to relinquish. Hillenburg passed away last year, but the series continues to follow his original recipe: eye-popping colors, a frantic pace and over-the-top antics.

“You get hit in the face, your face takes on the shape of a frying pan,” said Rodger Bumpass, who plays Squidward. “SpongeBob starts crying, he turns into a lawn sprinkler.”

Those ingredients are all on display in Friday’s special, which includes a raucous party in a pineapple house and a dancing can of beans. But the cartoon is more than just a visual feast.

“I think kids look at [SpongeBob] and he has the life they want,” said co-executive producer Vincent Waller. “He has a job he loves. He doesn’t have parents to answer to. He lives in a house by himself. But he is still obviously a child at heart. And they just go, ‘Oooh, I want that.’ ”

The show also connects with grown-ups.

David Bowie was a fan. Former president Barack Obama called it one of his favorite shows. At one point, roughly a third of the audience was above the age of 18. It’s not just because of the references to Led Zeppelin, Edgar Allan Poe and Pablo Picasso.

“It seems to be a refreshing breath from the pre-irony era,” Syracuse University pop-culture expert Robert Thompson once told the New York Times. “There’s no sense of the elbow-in-the-rib, tongue-in-cheek aesthetic that so permeates the rest of American culture. ... I think what’s subversive about it is it’s so incredibly naive — deliberately.”

Cast to be at MOA

The “SpongeBob” cast isn’t immune to their show’s charms.

Bill Fagerbakke, who plays slow-witted starfish Patrick, once bought some golf balls only because the box was in the shape of SpongeBob’s head. Lawrence snagged giant banners from the first movie after they were done hanging at her local mall. Bumpass claims to have the world’s largest collection of SpongeBob merchandise, including dental supplies and toilet-training gear.

“I have things that no one else can have, because they are signed by the cast,” he said. “I’m going to have an open house.”

Bumpass may get to hide behind an animated character, but that doesn’t mean it’s easy for him to go shopping without fans doing a double take.

“I was recognized at my dentist’s office the other day and I was like, ‘How in the world do you know me?’ ” he said.

Fagerbakke discovered that youngsters knew his “true identity” way back in Season 2 when he was picking up his daughters from elementary school.

“I had this kind of John Lennon buzz around the playground,” he said. “I was kind of stunned that the kids were so hip to it. I mean, I loved Looney Tunes, but I wasn’t wondering who Mel Blanc was.”

Anonymity in the Twin Cities will be even harder after a celebration Saturday at the Mall of America that includes a chance for fans to meet Kenny and Lawrence.

In Friday’s birthday special, SpongeBob bubbles to the Earth’s surface for a live-action interaction with cast members in a diner that has more than a passing resemblance to the Krusty Krab.

Kenny said the taping was a bit surreal, being on the set with his fellow actors dressed as their characters after two decades of working out of a sound booth.

“I don’t want to tell tales out of school,” Kenny said. But I think Clancy [Brown, who voices Mr. Krabs] put it perfectly when he looked around and said, ‘Wow, this is like having sex with the lights on.’ ”

Despite the hoopla, “SpongeBob” still has a long way to go before it’s the longest-running animated series in America. “The Simpsons,” “Arthur” and “South Park” all debuted earlier and are still in production. Still, the ocean’s highest-energy bottom dwellers hope to stick around. The network has not announced plans beyond this season, but it has greenlit a 13-episode prequel starring a 10-year-old SpongeBob during his summer at sleep-away camp.

“We want to last a little bit longer than the pyramids,” Bumpass said.