Tidepool Tim says,  "Truncate clams are so amazing to find.  Usually, we are collecting along amid the rocks and they just sort of appear.  The thick siphon or neck really looks like an elephants trunk! At first, I thought we had discovered some sort of mutated soft-shell clam.  To accommodate the long thick siphon, the shells of the clam are bulged out on the sides. It appears that sometimes they are embedded in a substrate that somehow washes away with tidal currents as these clams can be found barely buried into the beach.  Truncate clams are bivalve filter feeders and live up to 10 years in age.”