I'd mentioned fossil sharks teeth in an earlier post so I dug some out of the junk drawer and took a picture. St. Augustine's beach is divided by St. Augustine Inlet, Vilano Beach to the North, St. Augustine Beach South of the inlet. Vilano Beach has deep deposits of little Donax clam shells, and sometimes you can find a lot of fossil sharks teeth mixed in. Sometimes you can't, I don't know where they go, the ocean currents do strange things. Sharks constantly shed and renew their teeth, but these teeth are old, maybe thousands of years old. I've been told that the blacker they are the older. Sometimes a larger tooth shows up, but most are about like those pictured.
Click on the pic to see a larger version