Large Atlantic Surf clam shells from the coast of Maine. “The Atlantic surfclam (Spisula solidissima) is the largest bivalve in the western North Atlantic, reaching a maximum length of 226 mm (commercial minimum size: 120 mm in USA and 90 mm in Canada) and longevity of 37 years in the Middle Atlantic Bight population.”
I personally use my own as soap dishes, jewelry dishes, and business card holders.
The shells are each 1-2” deep at the deepest part and are available for sale by size at their largest measurement across. They are each 3-7” the hinge to the ventral margin.