I found this shell on a trip recently to Ft Clinch State Park, which is about as far north as you can go on the Florida East Coast before hitting Georgia (literally, the next island that you see from the fort is IN Georgia). The beach was not good for shelling; there was an acrid odor to the water, the surf was rough, and all that could be found was big, chunky fragments of mostly whelks. Almost all of the shells that I found had either worm tubes, or signs of small barnacles being once attached. One shell even had a strange green fungus. It was a pretty creepy experience.
Anyways, I found this odd looking scallop-like shell, and I cannot find out what species it is. I am hoping that someone will see this and recognize it. The shell has been identified as possibly being a fossil scallop!