Shell large, thin, white, with six whorls and a small but prominent inflated subglobular nucleus; spiral sculpture of numerous close-set rounded narrow ridges, of which part are larger than the others; on the early whorls two or three of the primaries are conspicuous on the periphery, with one or two finer ones intercalated; later the peripheral spirals merge with the other primaries, as to size and prominence, and on the last whorl there are four or five intercalary threads between the primaries, the space between the latter, from center to center, averaging 2.5min to each set; transverse sculpture shows only in fine, slightly irregular lines of growth; the whorls from and including the third are inflated, and the suture, though not channeled, is strongly marked; the canal is short and recurved, the siphonal fasciole indistinct; the aperture is wide, the outer lip, prominent iu the middle, receding toward the suture and the canal, smooth not thickened, whitish internally; inner lip concave, with a thin glaze of polished callus, slightly brown tinted; pillar twisted and the axis minutely pervious; the aperture longer than half the shell; operculum brown, moderately stout, apically pointed; maximum longitude of shell, 70; maximum latitude, 43; longitude of aperture, 45mm.
TYPE in United States National Museum. Type locality, Station 2839, near Santa Barbara Islands, in 414 fathoms.
RANGE. Pribilof Islands, Bering Sea, to Monterey Bay, California.

Type locality: "Albatross" st. 2839, near Santa Barbara Islands, California, - 414 fathoms, sand. Description: Shell small for the genus (usually between 57.9 and 78.4 mm), thin, rather fragile. Shape variable. Whorls convex, slightly shouldered. Subsutural slope narrow, straight. Colour snow-white, aperture occasionally yellowish. Sculpture consisting of numerous fine but sharp primary spiral cords, interspaces equally spaced, covered with fine secondary spiral cords. Two secondary spiral cords on subsutural slope slightly stronger.

Range: Neptunea amianta lives off western North America and is known from Canada in the north to California in the south. Bathymetric range bathyal and abyssal, down to 1590 m. Living on mud. Recorded from whale skeleton communities, the so-called "whale falls". Records from northern localities, as the Aleutian Islands and the Bering Sea, are found to be subadult Neptunea pribiloffensis.

Comparison: Neptunea amianta is characterized by having a white shell, with convex or slightly shouldered whorls and a fine spiral sculpture. Neptunea pribiloffensis is similar but differs in having slightly thicker primary spiral cords, usually a stronger secondary spiral cord in the middle of the interspace, a broad shape, a broad subsutural slope usually with only 1 slightly stronger secondary spiral cord, an angulated shoulder and usually a brown colour.
Neptunea humboldtiana is similar but differs in having smoother interspaces, a broad shape with convex whorls and deep suture, a shorter siphonal canal and a more prominent siphonal fasciole.