New York ? Nickelodeon boss Herb Scannell remembers his reaction to a rough cut of the very first “SpongeBob SquarePants” cartoon.

SpongeBob a bright-eyed, knickers-clad, sea-dwelling kitchen sponge had realized his lifelong dream: He got hired as a fry cook at the Krusty Krab diner, where, right away, he proved his worth by single-handedly serving an invasion of ravenous anchovies.

But here’s the kookie part: The sequence showing SpongeBob work his magic at the grill is accompanied by a 30-year-old recording of Tiny Tim warbling “Livin’ in the sunlight, lovin’ in the moonlight, havin’ a wonderful time!”

“When I heard that,” says Scannell, enjoying the memory, “I thought, ‘This show is gonna go places we don’t really expect.'”

And how. Premiering weekends on Nickelodeon in July 1999, “SpongeBob” won a weeknight berth two years later, and, soon after that, its benthonic hero was the biggest star in children’s TV.

“SpongeBob SquarePants” recently completed a year as the top-rated show on broadcast or cable among youngsters 2 to 11.

It routinely claims several of the top 15 weekly cable-ratings slots and soaks up 61.5 million viewers per month, one-third of whom reflecting its unexpectedly broad appeal are adults 18 to 49.

Another gauge of SpongeBob’s popularity is merchandising, which this year is expected to reach $600 million in retail sales. Nearly 100 companies are marketing SpongeBob fare that includes skateboards, beach towels and paper towels, backpacks and mac-and-cheese. Not to mention Halloween costumes: Look out soon for legions of SpongeBob trick-or-treaters.

Sweet innocence

Meanwhile, SpongeBob is headed to the big screen. After producing 65 half-hours for television, creator Stephen Hillenburg has begun writing a “SpongeBob” movie, scheduled to reach theaters in 2004.

“It’s gonna be long and hopefully funny, and it will star SpongeBob,” confides Hillenburg when pressed for details.

While acknowledging that “when you set out to do a show about a sponge, you can’t anticipate this kind of craze,” Hillenburg is willing to offer a theory for its success: “Spongebob is an innocent, and people respond to an innocent. I don’t think it matters if you’re young or old.”

“SpongeBob is childlike but not childish, a sort of boy-man like Jerry Lewis or Stan Laurel,” adds Tom Kenny, who supplies SpongeBob’s eager, braying voice he describes as “the Mayor of Munchkinland meets Elroy Jetson.”

Simpler to explain is the setting for “SpongeBob.” Hillenburg is a marine biologist-turned-animator.

But why, of all marine fauna, did he choose as his protagonist a sponge and a synthetic, manufactured-looking sponge, at that?

“Even among an odd group of characters,” Hillenburg reasons, “I thought that would automatically make him the oddest.”

But it’s tough competition in the seabed community of Bikini Bottom. There SpongeBob hangs out with his best friend Patrick, a dim-witted starfish; his sweetie, Sandy Cheeks, a squirrel from Texas who gets around in a diving suit; his cranky, clarinet-playing neighbor, Squidward; and his tight-fisted, er, -clawed employer, Mr. Krabs.

Together they enjoy a certain twisted cartoon logic that allows them, even in their watery world, to converse, sleep on linens with a pillow, sunbathe, fly kites and, of course, fry up those delicious Krabby Patties.

Simply absurd

A boisterous free spirit, SpongeBob exudes a happy-go-lucky attitude that “usually wins out,” says Hillenburg “or at least gets him into some interesting predicaments.”

In one cartoon, SpongeBob vies with Neptune, the sea god, to establish who can make the best Krabby Patties. In another, he forgets how to tie his shoelaces, then realizes no one else in Bikini Bottom knows how, either or even wears shoes. He frolics in an unexpected snowstorm; fails his driving test; gets lost delivering a pizza; sets out to meet his superhero idols, Mermaid Man and Barnacle Boy.

“There’s an almost Dali-esque level of absurdity that you can latch on to,” says Robert Thompson, professor of media and popular culture at Syracuse University. “But at the same time the show is intent on not being ironic or hip.”

“We just try to make ourselves laugh,” Hillenburg sums up, “then ask ourselves if it’s appropriate for children.”

For now, perhaps for good, production on the “SpongeBob” TV series has wrapped as Hillenburg turns his attention to the feature film.

“This is what Steve wanted to do: work on one thing at a time,” Scannell says.

Fortunately, Nickelodeon has stockpiled 15 unaired episodes to ration out before the film’s release. And Scannell looks forward to “SpongeBob SquarePants” going international with its goofy goodwill: Overseas TV sales are just beginning.

“It could be a kinder, gentler world,” Scannell says, “if SpongeBob became a global icon.”