monsterKing of the jellyfish? Or a giant, living, underwater doormat? Whatever your worst nightmare is, this ancient sea-bound entity could be it. LiveScience reports:

A mysterious fossil that has evoked images of a sea monster roaming the shallow waters of prehistoric Ohio [has] scientists stumped as to what kind of creature it was. One thing is sure: The enigmatic “blob” — discovered in elliptical pieces that, when fitted together, extended about 7 feet long, was once alive.

The team, along with the fossil hunter who discovered the 450-million-year-old specimen, suggest a range of possibilities: a type of huge algae or microbial mat, or even a member of the cnidarian family, which includes jellyfish (though scientists concede the jellyfish idea is highly unlikely).