Flood-tide, in sand, breaking cover before the water comes.
 
Mactridae: 34mm Spisula solida (Linnæus, 1758).
This Surf Clam is quite common in pure sand bottoms.
Two specimens found in coarse sand, 3m upon low tide line, 150m off Bon Secours Beach.
A sublittoral species, often found when snorkeling at low tide in large sandy bays.