This is the Norwegian Egg Cockle (Laevicardium crassum), a species of saltwater clam in the family Cardiidae that inhabits the Northeast Atlantic and the Mediterranean. It is recognisable by its smooth, oval shell featuring 40–50 faint ribs and a crenulated margin, with an exterior that is typically white or light yellow with occasional dark markings and a glossy interior.

Location:
Northeastern Atlantic—from Norway to the Iberian Peninsula—and the Mediterranean Sea, found buried in sandy or muddy substrates from intertidal zones to depths of approximately 200 metres.

Average Size:
Shells typically reach a maximum length of about 7.5 cm.

Family:
Cardiidae (Cockles)

Species:
Laevicardium crassum (formerly referred to as the Norwegian Egg Cockle)

Ecological Role:
As a sedentary burrower and filter feeder, the Norwegian Egg Cockle draws plankton and organic particles from the water, stabilising sediment and supporting marine ecosystems.

Conservation Status:
Not currently considered threatened. It is sometimes commercially harvested, though it plays a more critical ecological role in benthic habitats by aiding sediment stability.

Collection Date:
This specimen was collected on 9 June 1900.