Across the country, thousands of giant inflatable SpongeBob characters sit atop Burger King roofs, marking the release of The SpongeBob SquarePants Movie. But in recent months, an odd crime spree has gripped the nation, as over 50 inflatable characters have disappeared in various states.

It is uncertain who is responsible for the sponge-nappings or why they want the toothy Nickelodeon character, but investigators are on the case. Some of the nabbed figures have been returned, and at least one SpongeBob showed up on the Internet. On eBay, the roughly 8-foot-tall, knee-sock-wearing sponge was seen going for up to $510 at auction.

Burger King officials are scrambling to get a handle on the thefts, and spokespersons for the company insist that the disappearing sponges aren't a publicity stunt. Burger King officials value the balloon at $1,000, which makes stealing it grand larceny. Some Burger Kings are offering a tasty reward for the return of the SpongeBobs--a free Whopper each week for a year. The company has even set up a sponge-napping hotline so people can report the missing cartoon figure.