Appearance
The shell has a flattened globular shape, and reaches about 88 to 90 millimetres (3.5 to 3.5 in) in maximum dimension. The color of the shell is variable, but is often a greyish brown. The central apex of the shell is often a dark blue in fresh shells, which can make the shell somewhat resemble an eye. On the underside, there is a large brown callus which partly blocks the umbilicus of the shell.
The maximum recorded shell length is 82 mm.

