common or rough cockle?

common or rough cockle?

Observation - common or rough cockle?. Description: Solid shells, 4cm l& w, whiter near umbone getting redish / brown towards the outsite. Radiating ribs are rough but not spiny.

Solid shells, 4cm l& w, whiter near umbone getting redish / brown towards the outsite. Radiating ribs are rough but not spiny.