Brittle shell up to about 6cm in length and white to fawn in colour. Valve surface covered with fine concentric ridged and strong radiating ribs somes very coarse and bearing spines. Margin smooth except where the larger ribs meet it. Three cardinal teeth in left valve; right valve has two. Note - not typical of the Veneracea more like Pholadidae (piddocks) but lacks the very prominent cardinal teeth typical of piddocks.
Key identification features
- Left valve has three cardinal teeth; right valve has two none of which are long
- Brittle shell with fine concentric ridges
- Shell almost completely closes at anterior and posterior ends
Similar species
- Barnea candida has very prominent cardinal teeth in the hinge
Ecology and behaviour
Bores into hard clay, stiff mud or chalk/limestone. Probably imported with the American Oyster (Crassostrea virginica) at the end of the 19th century but is now well established.
Distribution and status
Alien
Recorded from the south of Norway to the Mediterranean and the Black Sea. Feeds by filtering phytoplankton from the water.