No magnet but while scuba diving have come across several handguns and lots of ammunition as well as the odd grenade. Only took a corroded revolver ashore but left the rest well alone. In deeper waters found the odd anchor and chain and once an old cargo boat. The cargo boat had been recorded as having sunk in a totally different location. We kept it secret as long as possible but some fool let the secret out and the wreckies moved in and stripped it in weeks for souvenirs probably now lying in somebody’s garage.