Shell size up to 2 mm (about 0.08 inch) in diameter. The shell has a low spire, is flattened, depressed, and the periphery (outer shell “edge”) is softly angled. The shell spire and base lack any sculpture except for coarse, irregular growth lines. The protoconch is "sunken" within the adult shell. The umbilicus is completely obliterated by a whitish, opaque callus that contrasts in color with the translucent-white remainder of the shell. (The species was named after Biscayne Bay in South Florida.) Photos by Patricia A. Starkey.