Shell inflated, with feather-like posterior incrustations; dorsal flange high. Length to 70 mm. The dorsal flange of this species is higher than that of the other two Californian species. In California, the incrustations may be massive and lack elegant, feather-like ridges. This led Hertlein and Strong (1946a) to propose the subspecies L. plumula kelseyi, but this character is too variable for taxonomic recognition. Monterey, California (36.6°N) [LACM, CAS], into the Golfo de California, south to Manta, Ecuador (1.0°S) (Olsson, 1961), probably to Perú; L'Île Clipperton; Islas Galápagos (1.0°S) [LACM]; Philippines, Australia; in the intertidal zone to 40 m, boring into shale, large mollusk shells, and dead coral. Also known from the Pleistocene of southern California.