Ribbed Saddle Oyster - Pododesmus patelliformis

Characteristics:

The shell is thin, especially the side attached to the foundation. The uppermost (left) valve is white or pale yellow with red or light brown stripes. As the name indicates, distinct ridges are radiating from the top. Old shells are usually covered by tubeworms and sponges. The diameter is less than 4 cm.

Habitat:

It sits attached to stones and other hard and smooth surfaces. It can be found on virtually any depth from the subtidal zone or deeper.

Distribution:

It occurs along the coasts of Europe, from western parts of Finnmark, Norway in the north to the Mediterranean in the south.