Scrub the clamshells under cold running water, using a stiff brush. Then soak the clams in salted water to expel any sand. Working over a plate to catch the juices, hold the clam with the hinged side against a heavy cloth in one palm. Insert a sturdy blunt-tipped knife between the shell halves.
Holding the shell firmly, move the knife blade around the clam, cutting the muscles holding the shell together. Twist the knife slightly to pry open the shell.
Cut the clam muscle free from the shell. To serve the clam on the half shell, use the deep half of the shell. Or, combine the muscle and juices for use in the shucked form.