I recently went diving about 1 mile off the coast of Venice Beach, FL. There are many fossil beds out there that you can dive and find various fossils including shark teeth. The site we went on was in about 30 feet of water and you would just lay on the bottom and scan around for something shaped like a tooth. We found fossils from lemon sharks, bull sharks, sand tiger sharks, and megaladon teeth. The megaladon teeth are estimated to be between 3 and 10 million years old. The other fossils pictures are sting ray barbs, whale rib bones and manatee rib bones.