Nice find! I know a guy in Leesburg, FL who has hundreds of these teeth in his collection. He finds all his one mile offshore of Shark Beach, Venice, FL. He paddles out a mile in his kayak, drops anchore, slips on a SCUBA tank and scours the bottom potholes for big teeth. He always dives alone, breaking a SCUBA rule. Hope to go out one day with a hookha rig and look for some for myself.
great looking tooth, but I don't think I'd be diving in the Potomac. Recent studies show some bad things happening to the fish there, not really that bad unless you consider male fish laying eggs and what not.