I found this last week beachcombing on Sand Key in Clearwater Florida. Just curious...At first I thought it was just a sea rock with worn holes. But then I noticed the tapered shape and the graduated concave grooves and center hole. Thinking maybe it is the mold of the inside of a seashell? Normally I don't find fossils there but sea was rough and I did find a piece of a fossil dugong bone the same day, which I normally never find there. It measures about 1.25" by 1.25" by 1 1/8". Darker color in grooves and center hole with some charcoal and golden brown hues. Any ideas what this could be?