I found the large clam shell on the left on Captiva Island near the Mucky Duck Restaurant at the end of August. Nearby are coquina shells. I looked through a seashell guidebook called Florida's Seashells, A Beachcomber's Guide and was unable to identify it. I posted this picture on the I Love Shelling Facebook page and didn't get a response. Hmmm... if anyone knows what it is, please leave a comment.
I've been in love with having sand between my toes since I was a teenager taking the ferry across the bay to arrive at Presque Isle State Park (aka The Peninsula) in Erie, PA.