These handsome reddish scallop valves are the Rough scallop.

On Sanibel in the beach drift this shell is a lot more uncommon than the Calico scallop, however the lovely red /orange/ brownish colors (plain or mottled) make them easy to spot.

The shell of this species can also sometimes be a beautiful bright lemon yellow in color.

When it is really fresh the valve is scaly on the outside, hence the name "rough scallop".

The valves are much less circular in outline than those of the Calico scallop.