Shell is relatively thick, heavy, compressed and rounded (small streams) or inflated and mostly triangular (big rivers). Umbo is low, slightly raised above hinge line and tilted forward. Greenish- to reddish-brown or light brown epidermis in juveniles and chestnut or dark brown in adults; usually without rays. Inside shell beak cavity is shallow (medium streams) to moderately deep (large rivers); pseudocardinal and lateral teeth well developed, with the lateral primarily straight; nacre (lining) white, occasionally pinkish.
Similar species: Round pigtoes are easily confused with Wabash pigtoes, which have a pronounced sulcus (a broad, groovelike indentation on the outside of the shell) and a square or triangular appearance.