Alasmidonta marginata shell description:

“Shell medium to rather large, long rhomboid, nearly or quite equilateral, subsolid to solid, subinflated;  beaks very full, high, sculptured with a few strong corrugations, which show a tendency to be doubly looped; posterior ridge very high and angled, ending behind in a point at the base of the shell, behind the ridge there is a decided oblique truncation and the truncated area is rather finely corrugated; growth lines uneven; epidermis smooth, shining, greenish, ashy or smoky-green with narrow yellowish rays and broken, clouded green ones; left valve with one small, compressed, sharp tooth in front of the beak; right valve with a small anterior tooth; laterals almost or quite wanting; beak cavities rather deep; nacre white or bluish, sometimes straw-color, rarely reddish or purple; prismatic border distinct” (Simpson, 2014; Mather, 2007).