(Fabricius O., 1780)
Description (shell):
Shell thin, tumid, oval, umbones anterior to midline. Sculpture of very fine concentric lines, growth stages clear. Lunule and escutcheon indistinct. Three cardinal teeth in each valve, anterior of right and posterior of left very reduced, inconspicuous. Adductor scars and pallial line indistinct.
Size:
Up to 3 mm.
Colour:
Off-white to light brown, sometimes pinkish dorsally. Periostracum smooth and glossy. Inner surfaces dull white to pale brown.
Habitat:
Intertidal only, on rocky shores. Attached by byssus, in holes and crevices, among or in barnacle shells and algae, often very common.
Distribution:
Distributed south as far as the Mediterranean, and north into boreal/arctic waters, where it is apparently circumpolar in distribution (Distr. T. minuta).