Size: Up to five inches.
Shape: Elongate, with a broadly curved dorsal margin and slightly concave ventral margin.
Periostracum: Light brown (juveniles) to dark brown or black. No shell rays, but growth lines are prominent and heavy.
Lateral Teeth: One poorly defined lateral tooth on each valve, though these are sometimes hard to distinguish.
Pseudocardinal Teeth: Right valve has one triangular-shaped tooth that is slightly down-turned. Left valve has two triangular-shaped teeth; the posterior tooth is larger with a ragged edge, and the anterior tooth is smaller and sometimes indistinguishable.
Nacre: Usually purple, salmon-colored, or pink (sometimes white). Nacre color fades to white over time. Anterior adductor muscle scar is sharply defined, whereas the posterior adductor muscle scar is less defined. Tiny faint pits are sometimes evident on the central part of the nacre.