Description: This bivalve has two brittle, equal valves and a distinctive elongated oval outline, with a gape at one end. The valves are white and it can reach up to 6.5 cm long. Outer surface may be covered in part by the thin periostracum, which ranges from light brown to yellowish. There are concentric ridges and radiating ribs on the outer surface of the valves which form small spines where they cross each other. These spines are more prominent towards the front of the shell, where they are also visible along the margin of the shell. Chondrophore (protruding platform under beaks) is longer in the left valve than right, in fact the left often overlaps the right when the shell is closed. Shell interior is glossy white and some of the external ridges and rays are visible. Pallial sinus is deep and extends as far as the midline.

Habitat: Bores into a range of materials including peat, wood, mudstone, maerl, chalk and sand. Found from the intertidal zone to 5-6 m depth.

Distribution: Recorded from most coasts around Britain and Ireland where there is suitable habitat. Seems to be rare in Scotland.

Similar Species: Could be confused with Barnea parva, which has a more solid shell and more irregular outline and inflated appearance. See also the American piddock Petricolaria pholadiformis and common piddock Pholas dactylus.

Key Identification Features:

• Brittle valves.
• Distinctive elongated oval outline.
• Concentric ridges and radiating rays on outer shell surface.
• These form small spines where they cross.
• Chondrophore longer in left valve than right.
• Deep pallial sinus, extending to midline.

Distribution Map from NBN: Barnea candida at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Barnea candida at iNaturalist World Species Observations database.

GBIF data for Barnea candida

WoRMS: Barnea candida at World Register of Marine Species. Accepted name: Barnea candida (Linnaeus, 1758). AphiaID: 140767.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Heteroconchia; Euheterodonta; Imparidentia; Myida; Pholadoidea; Pholadidae; Pholadinae; Barnea