Probably different species.
Lamp shells found washed up on the beach. The whole critter is 2 shells together, one wider and a different shape to the other.
Found on the beach. Obviously from two different individuals. In this area, regularly seen attached to shallow subtidal rocks.
Many of these found washed up on the beach.
Photo scanned from 35mm slide.
Found in dredge near Friday harbor labs. Various sizes and ages. Found literally hundreds in 2 dredges
The Rhynchonellata is a class of Lower Cambrian to Recent articulate brachiopods that combines orders from within the Rhynchonelliformea (Articulata revised) with well developed pedicle attachment. Shell forms vary from those with wide hinge lines to beaked forms with virtually no hinge line and from generally smooth to strongly plicate. Most all are biconvex. Lophophores vary and include both looped and spiraled forms. Although morphologically distinct, included orders to follow a consistent phylogenetic sequence.