Bent-nosed clam (macoma nasuta)
If you dig in the high intertidal zone of a mud flat in Puget Sound, this is one species of clam you will almost always find there as it can tolerate low oxygen conditions as well as fine mud.
The bent-nose clam is a small, native species averaging around 2 inches long. It is characterized by the up-turned or bent portion of the shell as shown in the edge view insert in the photograph. Otherwise it has a normal clam appearance when seen from a side view. Also shown is the inside of a broken clam with the long, orange incurrent siphon above the short excurrent siphon and the curved digging foot on the bottom.
The animal lies on its side buried some 4 to 8 inches in the mud. The incurrent siphon pokes through the upward pointing bent shell and winds its way to the surface. There the siphon sucks in surface material of diatoms and other small bits and pieces of plant and animal debris bringing it down the the clam. There the gills extract food as well as oxygen from the incoming water.
Using its foot, the clam can dig, but in a sideways motion rather than straight down as in other clams.
These clams were eatable if allowed to purge themselves of sand and mud by holding in clean saltwater for several hours. However, they are little used today.
Source: David W. Jamison, a marine biologist and Boston Harbor resident