Well, I'll be an absorbent invertebrate. Has it really been 10 years since we first met a happy little cartoon sponge that lives in a pineapple under the sea? You'd better believe it. 'SpongeBob SquarePants' celebrates a decade of underwater delirium this month, and Nickelodeon is making a big splash to celebrate with a 'SpongeBob' documentary and weekend marathon. The fun starts at 8 p.m. Tuesday on VH1 with 'Square Roots: The Story of SpongeBob SquarePants,' a star-studded original documentary that chronicles the animated life of the boxy yellow dude. SpongeBob mania then kicks into high gear with a 50-hour marathon of classic and new episodes running Friday night through Sunday. For 'SpongeBob' executive producer Paul Tibbitt, 10 years of 'SpongeBob' is a lot to soak in. 'I got a feeling early on that it would at least be good, a good cartoon,' he says. 'As far as being on for 10 years and all the other stuff that comes along with it? No idea. I don't think anyone really knows when that's going to happen.' 'SpongeBob' creator Stephen Hillenburg developed the character back in the '80s to amuse kids at the Orange County Marine Institute in California. The former marine biologist gave those doodles new life when 'SpongeBob SquarePants' debuted July 17, 1999. Tibbitt has been with the show from the beginning, first as a writer and director and now as executive producer. 'Steve had a really solid idea of what he was doing before he even madeww the pilot,' Tibbitt says. 'I think still to this day, this many seasons in, we're finding new channels of humor for SpongeBob.' That humor is as innocent and earnest as it is manic and quirky. Broad appeal Tibbitt says SpongeBob is up for anything and tries to find the bright side in every situation -- good intentions that naturally result in wackiness for him and fellow Bikini Bottom cohorts Patrick (a dim-bulb starfish and SpongeBob's best friend), Sandy Cheeks (a sassy squirrel in an astronautlike outfit), Squidward (a grouchy squid) and Mr. Krabs (a penny-pinching crab). 'We knew we were making a cartoon for Nickelodeon, which is mainly watched by children,' Tibbitt says, 'but we never really set out to pander or talk down to kids. ... Luckily there were some adults paying attention while the kids were watching.' That cross-generational fan base speaks volumes with its remote controls as well as with its wallets. Solid ratings Nickelodeon says 'SpongeBob' averages 70 million viewers a month and has been the top animated program for ages 2 to 11 for more than seven consecutive years. As for all those SpongeBob plush dolls and other items, the network figures the franchise pulls in almost $8 billion a year in retail sales. Take that, Bart Simpson. Speaking of 'The Simpsons,' 'SpongeBob SquarePants' boasts its own share of celebrity guests. John O'Hurley of 'Dancing With the Stars' fame has lent his comically haughty voice to King Neptune, and Gene Simmons used his infamous tongue to voice the one-eyed Sea Monster. And who could forget Ernest Borgnine as Mermaidman and Tim Conway as Barnacleboy a nutty, nursing-home spin on DC Comics' Aquaman and Aqualad. (Tibbitt wrote the episode that debuted the duo, by the way.) Johnny Depp, David Bowie and Amy Poehler have also made vocal contributions to the cartoon series. Tonight's 'Square Roots' features commentary from Hillenburg and celebrity SpongeBob-speak from the likes of LeBron James and Ricky Gervais, who'll star in a fall 'SpongeBob' special with Will Ferrell and Robin Williams. But for all that star power, Tibbitt says celebs dig 'SpongeBob SquarePants' for the same reason parents without paparazzi love the cartoon: It's a show they enjoy watching with their kids. 'I'm always for anything that brings kids and adults together,' Tibbitt says. 'I had somebody tell me once that 'the day that my son graduated from Barney to SpongeBob was a very good day for us.' Just sort of knowing that parents aren't going to want to tear their hair out and run out of the room when our show comes on, that's nice because people should watch TV with their kids.' ------ SOAK UP SOME FACTS -- SpongeBob SquarePants made its official debut July 17, 1999. -- In January 2000, SpongeBob SquarePants premiered in global markets, starting with Australia. -- SpongeBob did his first 'Got Milk?' ad in 2001, followed by one in 2003. -- Katie Couric dressed up as SpongeBob for Halloween 2002 on the Today show. -- SpongeBob debuted in the Macy's Thanksgiving Day Parade in 2004. -- In 2005, more people tuned in to SpongeBob SquarePants on Canal 5 in Mexico than to the presidential election. -- SpongeBob was made an honorary citizen by the mayor in Bottrop-Kirchhellen, Germany, in March 2007. -- In 2008, Dave King of Belvidere, Ill., spent more than 30 hours building SpongeBob, Patrick, Gary, Squidward and Plankton out of snow. ------ NO REASON TO LEAVE THE PINEAPPLE Nickelodeon calls it the 'Ultimate SpongeBob SpongeBash Weekend.' 'SpongeBob SquarePants' geeks call it 50 hours of cartoon nirvana. Here's a rundown of the show's 10th-anniversary marathon. Friday The 50-hour frivolity begins at 7 p.m. with the premiere of 'To SquarePants or Not to SquarePants,' which sees our little yellow hero facing life with -- gasp! -- round pants. Saturday At 9 a.m., fans weigh in with their 10 most memorable SpongeBob episodes. For a nightcap, enjoy 'The SpongeBob SquarePants Movie' at 7 p.m. Sunday It's another top-10 countdown at 9 a.m., this time with celebrity-picked episodes. The marathon wraps with 10 all-new premieres starting at 6 p.m 