During a recent beach walk a friend explained to another what made the holes in the rocks, “Boring Clams, literally.” I just couldn’t help myself, “Well, figuratively, too. If you invite them to your party, they won’t dance, they’ll just sit there. They really are boring clams!” Ba-dum-tshh!
All kidding aside, it is the Piddock or Boring Clam (Penitella penita) that uses the rough ridges on its shell to slowly grind a hole into rock where it will stay for the rest of its life. Lucky for them, most of the rock up here is a fairly malleable mudstone.