Specimen collected by Jan Light from The Fleet, Weymouth, Dorset. Length = 20mm.
<em>Irus irus</em> (Linnaeus, 1758)
Recorded from the south and west of the British Isles and south to the Iberian Peninsula and into the Mediterranean and Black Sea.
Lives in holes in limestone (often previously occupied by other species) or in crevices in Laminaria holdfasts. Feeds by filtering phytoplankton from the water.
Brittle shell up to about 2.5cm in length. Dirty white or fawn in colour. Inside white or cream often with purple stain. The degree of distortion and sculpture of the shell depends on how tightly the specimen was wedged in the cavity in grew in. The frill like concentric ridges can be very prominent.