Description: This bivalve is solid with a distinctive shape. One half is broadly triangular in outline with the other is broadly oval. There are also large gapes at both ends of the shell. It is white with a pale brown periostracum and reaches up to 9 cm in length, although it is much more commonly smaller in size. There are concentric ridges on the outside of the shell which form a very rough surface, and there is a spiked margin to part of the shell. Pallial line is thick and curves back into the deep pallial sinus.

Habitat: Found from low water down to around 10 m, bores into soft sedimentary rock.

Distribution: Recorded from most coasts of Britain and Ireland, but seems very rare on southern and western coasts of Ireland.

Similar Species: Unlikely to be confused with any other species.

Key Identification Features:

• Distinctive shape, half triangular and half oval.
• Concentric ridges on outside of shell make surface very rough.
• Large gape at both ends of shell.

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

iNaturalist: Zirfaea crispata at iNaturalist World Species Observations database.

GBIF data for Zirfaea crispata

WoRMS: Zirfaea crispata at World Register of Marine Species. Accepted name: Zirfaea crispata (Linnaeus, 1758). AphiaID: 140771.

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