Utterbackiana suborbiculata shell description:

"Shell large, irregularly short ovate, thin but strong, gaping in front and behind, subinflated, with low beaks, which are compressed in young shells but fuller in old ones, their sculpture a few irregular, feeble undulations, each bar usually having small, sharp tubercles, these tubercles form two imperfectly radiating rows; dorsal line somewhat curved, ending in front and behind in a small wing or angle; dorsal slope truncated, its outline incurved just above the low posterior ridge; the rounded posterior point about at the median line; base line rounded; anterior end rounded, sometimes cut away a little below; surface smooth and shining in young shells, pale, yellow-green, beautifully and delicately rayed, with three broad rays behind; in old shells the outer growth is concentrically sculptured and the epidermis is smoky or ashy, often banded and nearly or quite rayless; nacre silvery and iridescent, tinted bluish or purplish” (Simpson, 1914; Mather, 2007).