The most common barnacle on the west coast is  Balanus glandula ("BAL ah nuss GLAND you lah").

The acorn barnacle, is a small, whitish, shelled crustacean which can be seen in the thousands on most of our shores

Although it seems inactive during low tide the barnacles close up and will apear dead.

Common Barnacle

Drawing by Iris Churcher, Malaspina University-College