Fossarus garrettii Pease, 1868. (Synonym: Adeorbis costata Garrett, 1857, non Brocchi, 1814.) Length, 4 mm; diameter, 3.5 mm. Shell: turbiniform, solid; with prominent spiral keels; white. Spire: protoconch of two obliquely set brown, cancellate whorls; teleoconch of three whorls, the last the largest. Sculpture: three or four prominent spiral cords, the interspaces approximately one-third the diameter of the cords with fine spiral threads. Aperture: subovate, outer lip reflected outward; umbilicus narrow; base with a projecting flange separated from the columella which is reflected over it. Color: white.
Specimens are occasionally found under rocks in tide pools; beachworn shells are common in drift.
F. garrettii may be endemic to the Hawaiian Islands; it is distinguished from F. trochlearis (A. Adams, 1855a) from the Seychelles, Bombay, New Caledonia, and southern Japan by its more obtuse shape, shorter spire, wider, grooved keels, and regularly striate interspaces.