The balloons of the wildly popular Nickelodeon character started appearing at fast-food restaurants on Nov. 11 in a promotional tie-in for his new film, "The SpongeBob SquarePants Movie."
Who's snatching the balloons? "One theory is that Plankton who, as fans know, has a rival restaurant -- it could just be professional jealously," Burger King Executive Vice President Russ Klein joked with The Early Show co-anchor Rene Syler.
"We're not quite sure what a SpongeBob might do after he leaves the top of a Burger King roof," Klein continued. "We've heard reports of him being auctioned off in various forums, and we just hope for his safe return, and any help the public can provide in terms of his safe return would be appreciated."
Some of the bigger-than-life-sized versions of "The SpongeBob Square Pants Movie" star have turned up on eBay.
EBay spokesman Hani Durzy said stolen property is not allowed on the site, but it's almost impossible to know what's stolen and what's legitimately acquired. "We're in no position to know exactly how anyone gets the items they sell on eBay," he said.
Durzy said that if someone thinks an item on eBay is stolen, they should contact police, who will then contact eBay.
"As long as there is a police report filed for stolen property, we will take listings down," he said.
Klein confirmed to Syler that Burger King has received ransom notes for the SpongeBobs. "But," he kidded, "Mr. Crab is a penny-pincher and he's been very firm about no rewards for Spongebob's return.
"(The ransom notes) have requested various items like crabby patties, Burger King shakes and fries. And, again, while we'd love people to come back and participate at the restaurant, Mr. Crab just feels like a reward is too much to expend," Klein said.
"We think that Plankton is our prime suspect, and because there have been a number of disappearances, I think the rumors of a conspiracy in that these vanishings are connected in some way is probably inflated, if you know what I mean," Klein added.
"It's a peaceable kingdom at Burger King and our objective is to get every SpongeBob back on the rooftops of Burger Kings, unharmed and full of air."
Jim Twitchell, a professor of advertising and English at the University of Florida, suspects young men are behind most thefts of the famous Krabby Patty flipper.
"They will show up in fraternity houses for sure," he said.
A Burger King near Palatka, south of Jacksonville, is among the latest to report the theft of the $500 balloon.
"We don't have any theories. SpongeBob SquarePants is kind of a fad. It could be a childhood prank or an adult trying to get a fad item for Christmas," Sheriff's Lt. Steve Rose said Wednesday. "If any leads come across, we will follow up in hopes of making an arrest."