Extreme maximum length 30mm, but in Portugal usually 10mm or less, occasionally 20mm. Elliptical outline, low profile. Ample, soft, translucent, white mantle covers whole body [image 1]; covered in low soft translucent tubercles, inconspicuous unless seen in profile . Irregular line of opaque white tubercles (defensive glands?) around mantle skirt .
Small whitish apex; white stem; and about 7 – 9 lamellae, usually dark chocolate brown, occasionally reddish brown or almost black.
Four to seven plumes, with stout main rib, short stout branches and short pinnae; sparse overall appearance when expanded. Brown, similar shade to rhinophores, apart from medially-white main rib . Able to contract  or retract completely.
Thin, translucent white, almost transparent, with opaque white flecks concentrated at periphery. Concealed when at rest; projects from posterior of mantle when extended in motion . Anterior and sole; no information.
- Low profile, soft, translucent, white body, sometimes tinted yellow.
- Opaque chalk-white or lemon-yellow glands around mantle skirt.
- Rhinophores and gills white.
Portugal to extreme SW tip of England (first record 2012, second 2013), and Mediterranean coast of Spain and France.
The map provided here shows the distribution of the species based on Conchological Society data.