Lamellaria latens (O F Müller, 1776)
Author & date of last revision: Ian Smith on 18 December 2012
L. latens is a slug with no visible shell when alive, but it and L. perspicua are more closely related to the majority of sea snails, especially the cowries [Lp13], than to the bulk of sea slug species.
Usual length to 10 mm, width to 6 mm. Flexible, varies between flat [image3] and upturned saucer . Body dorsum nearly smooth, with a few small tubercles . Ground colour  of dorsal surface light sandy brown, yellowish, or off-white. Surface usually has small black or sepia flecks  that mimic small inhalent pores on compound ascidians such as Trididemnum (EML). Also markings of various colour, including pure white, ochre and yellow which may be arranged to resemble larger exhalent openings of compound ascidians. Yellow marks are often found near the mantle edge . Front edge of mantle curved into a cylindrical siphon with a cut along anterior face, so can be uncurled  at times. Underside of mantle and upper surface of foot may be speckled with fine light grey flecks . No gills or tentacles on the dorsal body surface . Smooth tentacles and no snout on head . Underside of foot paler  than dorsal body surface. Slit runs across underside of foot near front edge.
Longest dimension to about 5 mm, width to about 4 mm. Permanently enclosed in body, fragile, translucent white. Large aperture, so boat or ear shape. Spire barely perceptible, does not protrude beyond outer lip of aperture when shell viewed in plan . Rarely washed up intact.
Possible ambiguity over shell sizes in published accounts because of difficulty in measuring conventional height (apex to furthest point of aperture) of these fragile and unusually shaped shells, and perhaps confusion in collections of shells of L. perspicua and L.latens. Longest dimension of shell is usually half length of body.
Key identification features
Some white animals resemble L. latens, and require examination of shell spire for positive identification if length of animal 10mm or less.
Ecology and behaviour
Low water spring tide to more than 100m. On or under stones and rock ledges, in rock pools and in Laminaria holdfasts near its compound ascidian prey, including Botryllus (EML), Polyclinum (EML), Leptoclinum and Trididemnum (EML). Male has external penis. Egg capsules inserted into ascidians. When covered in water, echinospira larvae with an inner and outer shell are released to drift in the water column before settling on the sea floor and transforming into the adult form.