Shell is stout, moderately inflated and elongate; posterior end pointed (males) and broader and squared off (females). Umbo slightly raised above hinge line. Epidermis is dull, greenish-yellow in juveniles, becomes dark brown to black in adults, often with dark green rays that may become less distinct with age. Inside shell beak cavity is shallow; pseudocardinal teeth thin, triangular and nearly parallel to one another; lateral teeth long, thin and straight; nacre (lining) white, iridescent posteriorly.
Similar species: Black sandshell is glossy, darker, longer, larger and heavier with pointed posterior end. Spike has a thicker, heavier shell, not as inflated with well-developed teeth. Little spectaclecase is thicker, more oval and inflated.