Vernacular names: Spotted cowrie; European cowrie; Grottie-buckie (Scots); Cragen Fair (Welsh);
10mm to 12 mm high (longest dimension of shell) by about 8mm wide.Typical ovoid cowrie shape. Solidly built with about twenty strong transverse ridges and intervening grooves. Spire hidden from view by the enveloping final whorl [image8]; a slight bump on the posterior end may indicate its position.Ventral surface white with a slit aperture.On the rest of the shell the ridges are pinkish white with pink to dark pink intervening grooves, and there are three dark marks of varying intensity on the dorsum .
White flimsy shell . Up to 12 mm high (longest dimension of shell). Last stage juveniles  can be larger than early adults. Under 7mm high the juvenile shell  has a typical gastropod aperture and spire, and lacks any sign of ridges. At 10mm high  the spire is very small in proportion to the final whorl, the aperture is a slit, and white ridges are developing on the ventral surface. Shape more ovoid. At 12 mm high  the spire is even smaller in proportion to the final whorl, the aperture is a slit, and ridges are appearing on both ventral and dorsal surfaces. During transformation to adult, the spire is completely enveloped by the final whorl.
The mantle is drawn out at the front of the animal into a cylindrical respiratory siphon with a slit down its anterior face. Head, smooth tentacles and siphon are orange in adults , with many yellow longitudinal lines on the dorsal surface of the foot , and yellow spots on the tentacles and siphon. The mantle, can envelope the whole shell , or be completely withdrawn . It is greyish white, heavily marked with dark, often purplish, patches aligned with the shell grooves. Small yellow tubercles are scattered sparsely over its surface. The free edges of the mantle are orange.
Key identification features
Ecology and behaviour
Sublittoral, and near LWS on rocky shores. On or under stones and rock ledges near its compound ascidian prey, including Diplosoma (EML), Botryllus (EML), Botrylloides (EML) and Polyclinum(EML). The mantle can emit acid in defence. Vase-shape egg capsules are inserted into ascidians up to the neck of the vase. When covered in water, echinospira larvae are released to drift in the water column before settling on the sea floor and transforming into the juvenile shell form.