Even hard shell clams (quahogs, cherrystone, little necks, chowders, etc.) aren't immune from green crabs.

Check out the chipping along this cherrystone. That is work of a green crab trying to have dinner. Looks like it gave up. If they can chew up hard shells, imagine what they do to soft shells, mussels, razors, and oysters, which have much thinner shells around their "mouth"!!