Shell large, round or somewhat quadrate, thin to moderately thick (particularly in older individuals), and inflated. Anterior end rounded, posterior end bluntly pointed (males) to truncated (females). Dorsal and ventral margins straight to curved. Umbos turned forward and elevated above the hinge line. Beak sculpture of four or five elevated ridges. Periostracum smooth, yellow or yellowish green, usually with numerous dark green rays of various widths. Length to 7 inches.

Pseudocardinal teeth relatively large, elavated, and roughened in young individuals, smoother in old specimens; two in the left valve, one in the right. Lateral teeth straight to curved, moderate in length, and striated. Beak cavity deep. Nacre white or bluish white, occasionally pink or salmon, iridescent posteriorly.