Shell is large, very compressed and rounded with a large wing above the hinge line. Umbo is flattened, small and not raised above hinge line. Green or greenish-brown epidermis, often with faint rays, becomes dark brown to black with age. Inside shell beak cavity shallow; pseudocardinal teeth large; lateral teeth bladelike and poorly developed; nacre (lining) bluish-white to white, iridescent posteriorly.
Similar species: Pink heelsplitter is more inflated with a pinkish-purple nacre. Pink papershell is generally smaller with a thinner shell and purple nacre.