Do you love walking along the beach collecting shells? Do you wonder just what kind of shell you have picked up? We will try to help you find out with this simple breakdown of the most common shells you might find on Pacific Northwest beaches.

Mussels,oysters, clams, and cockles are all bivalves. That means they have two shells, a top and a bottom.

Pacific Blue Mussel

Mussel shells are symmetrical, elongated and typically attached in  clumps by a strong threadlike secretion. They are very common on  floating structures, pilings and intertidal and sub-tidal rocks and gravel. The most common mussel in the Pacific Northwest is the Pacific Blue Mussel.

The lower half of an oyster shell is usually cupped and often attached. The upper shell is flattened and smaller than the lower shell.The oyster is often found in protected waters in the intertidal zone. Only one species of oyster , the Olympia Oyster, is native to this coast.

The horse clam, the butter clam, the bent nosed clam and the razor clam are the most common species of clam that can be found in this area. Most of these clams are found in the intertidal zone in sand or mud. The butter clam is most often found on gravel beaches while the razor clam is just

Littleneck Clam

under the surface at lowest tides on surf beaten sandy beaches.

The ribbed little neck clam is found on gravel, sand beaches buried close to the surface.

Whelks, limpets and chitons are also found on intertidal rocks or in splash zones. Whelks are lovely shaped shells.They are the most fun to find.


The limpet looks like a Japanese miniature hat and the chiton has 8 overlapping plates bound together with a leathery girdle. These last two are often found washed up on docks.To find pictures of Limpets, chitons and more shells please go to

Happy Shell Hunting!



Tidepool and Reef   by Rick Harbo  1999

Pacific Reef and Shore  by Rick Harbo 2003