Deputies in the Florida Keys have cracked a spooky underwater mystery.

A sponge fisherman called Monroe County Sheriff's deputies on Monday and reported seeing what looked like a human torso sitting on a captain’s chair about three feet underwater.

Detectives took a boat ride to the area where the fisherman reported seeing the remains several miles west of Key West.

When divers brought the skeleton into the boat, they found it was fake. Someone had attached part of a plastic skeleton to the chair and put it underwater.

“It looks pretty real,” said Detective Manny Cuervo. “But if it was real, the skeleton would have fallen apart long before it had time to accumulate all the algae that was on it.”