Size small, up to three-quarters of an inch in diameter (21 mm); height, a little more than half the diameter. Shell broadly conic, cylindric when crowded. Walls solid, with no parietal tubes. Wall-plates smooth near the apex but usually strongly ribbed in the lower half. External sculpture influenced by pattern of surface to which it is attached. Inner surface with fine small regular ribs, denticulate where they unite with the base. Base solid with shallow grooves radiating from the centre. Orifice pointed at the carinal end, rounded at the rostral end. Sheath, short; scuto and terga near the margin of the orifice.
Dirty white with thin yellowish epidermis.
Monterey, California, north to Alaska. Most of those collected have been taken by dredging at depths ranging from 10 to 35 fathoms.
B. hesperius laevidomus grows on various mollusk shells, especially on Pecten, moon-shells and clam-shells and less commonly on other mollusks, brachiopods, crabs, tunicates, and other barnacles. It is found most often associated with B. crenatus and less commonly with B. balanus pugetensis and B. rostratus alaskensis. B. hesperius laevidomus is very often the only barnacle represented in dredge from a muddy bottom." (Henry, 1940).