Photo scanned from 35mm slide.
Black brachiopod frequent here
Found in dredge near Friday harbor labs. Various sizes and ages. Found literally hundreds in 2 dredges
I cannot remember which Brachiopod order this living specimen belongs to. I think Terebratulida.
you can tell it is a brachiopod and not a limpet or hipponicid by the ring of hairs extending from around the shell.