FOUND WHAT APPEARS TO BE AN OLD SALTWATER CORRODED COIN ! HOW DO I GO ABOUT DE-CORRODING IT ? IT READS NICKLE ON THE CORTES AND IS ABOUT THE SIZE OF A DIME OR PENNY AND JUST HAS CRUST ALL OVER AND DOES NOT APPEAR TOTALLY ROUND LIKE MAYBE A LITTLE CHIP OUT OF THE EDGE AND I FOUND IT IN AN AREA THAT THE SPANISH INHABITED SUPPOSEDLY BY THE WATER IN SHELL HARD BEACH LIKE ! HELP LOL