Valves bluish grey, moderately thick, somewhat translucent with distinct growth lines; lines from umbones lacking or only apparent as faint traces. Gaps between scutum and tergum narrow, that between carina and scutum broad and dark purplish brown. Scutum subtriangular with secondary area between umbo-apical ridge and occludent margin fairly conspicuous; occludent margin rather convex; no inner tooth on right scutum. Tergum triangular with convex dorsal margin. Carina narrow, base ending in a fork a little beneath basal margin. Peduncle as long as or shorter than capitulum; a pale or orange belt below capitulum.
Mouthparts and cirri lacking any important specific characters. Three filaments of body on each side beneath cirrus I. Caudal appendage smooth and rounded.
Specimens of L. hilli have sometimes been misidentified as Lepas anatifera. The filamentary appendages are a good distinguishing character. There are three in L. hilli, and in L. anatifera two or occasionally only one on each side of the body. The broader gap between scutum and carina in L. hilli is typical and there is no internal tooth on the right scutum.
Length of capitulum up to 40 mm.
Valves bluish grey.
Distribution in the North Sea:
Carried into the area from warmer seas on ships' hulls.
Circumglobal in tropical and subtropical waters, transported by ships to boreal waters.