This species is widespread, occurring from South Africa, through the Indian Ocean and Indonesia, and north to southern Japan and east to Hawaii. It is often found in high densities where it occurs. The shell is strombiform, with wide, rounded axial ribs. Adults are 4 to 5 mm in length with 2.75 to 3 teleoconch whorls. The columella has one strong fold rather than two. The protoconch is prominent, usually pink, with 4.5 to 5 whorls and axial threading over at least the first protoconch whorls; the axial threading tends to disappear in the middle of the later protoconch whorls, though it may simply be worn off in most specimens. The early spire whorls have similar sculpture to the body whorl, with the addition of a weak subsutural groove. The shell varies in colour and pattern, but is frequently pink with white and occasional tan markings.

Protoconch of about 4,5 finely axially costate whorls. Adult shell biconical, variable in shape and colour; number of axial ribs varying from 14 to 28 on penultimate whorl. Development of axial ribs on last whorl also variable: these sometimes extend to base, sometimes to midwhorl, and in other individuals they evanesce; more rarely, several or even all whorls may be smooth. A syntype of ionida in MNHP that we examined bears 16 full axial ribs. Ground colour varies from dark pink to creamy white or yellowish, with a variable pattern of spiral rows of white blotches and darker spiral lines. Spiral striae are limited to the base. The columella bears a single denticle, which does not conform with the other species in this genus. However, Sleurs (1982: 197) considers it as a member of this genus, on account of the sculpture of its protoconch. Adult length varies from 3,2 to 6,2 mm.
The variation that we have observed in a sample of more than 1 000 specimens includes forms quite identical to the type-figures of C. liocyma, C. scalpta, and C amirantium, and all intermediates between these and quite typical specimens of C. ionida are present. C. liocyma was based on slender specimens, and C. scalpta has a particular pattern of zigzag lines, but intermediates exist.

As Columbella amirantium E. A. Smith, 1884 :
Shell small, broad, ovate-fusiform, subpellucid, with the upper part of the whorls whitish and pale pink beneath, ornamented with some opaque white spots below the suture and a band of small dots of the same colour round the middle of the body-whorl, the basal extremity of which is dark pink or black dotted with white. Whorls 8; five nuclear convex, pink, finely longitudinally lirate; the rest strongly costate and rather convex at the sides. The ribs are thick, rounded, about sixteen in number on the penultimate whorl, subobsolete behind the labrum. The last volution is broad above, contracted inferiorly, the extremity being crossed by several coarsish grooves and ridges. Aperture narrow, only a little narrowed anteriorly into a slightly oblique open canal. Outer lip much thickened by a strong external white varix, marked with two brownish-pink spots, one above and the other below the middle; it is also internally thickened, armed with eight denticles, and subsinuated at the upper end. The columella is covered with a callus bearing about five small tubercles near the middle. Length 5,7 mm., width 3 mm. Eagle Island, Amirantes, 12 fms.; sand and coral bottom. This is a very pretty little species, having the same form as the typical group of the genus.

Glossy, creamy-white or yellow to dark pink with a variable pattern of spiral lines and rows of white blotches, occasionally with zigzag lines. Whorls convex; axial ribs 12-14 on penultimate whorl, on last whorl may extend to base, to midwhorl, or may be absent. Base of last whorl with 8-12 low spiral threads. Columella callus with outer edge slightly raised, columella bearing 3-4 denticles on its outer edge, inner edge with one oblique denticle. Outer lip thickened in middle, with 7-8 distinct denticles. Length ca 6 mm.
Distribution and habitat: Japan to northern Transkei, living under stones, usually subtidal to about 50 m.

Note: Synonyms include ColumbeUa amirantium E.A. Smith, 1884, and ColumbeUa sigma Barnard, 1959; the holotype of the latter is a juvenile shell of ionida. A beautifully coloured species, fresh shells of which are occasionally found in beach-drift.
Types: C. ionida, syntypes, in MNHN; type loc. not given [= Reunion Is., des. Drivas & Jay, 1990]. C. amirantium, syntypes, BMNH 1882.12.6.140-2; Amirantes Islands, Seychelles. C. sigma, holotype, SAMC A8890; the given type locality of ‘Cove Rock' (East London), 41 m, is probably the result of mislabelling of Natal material (not uncommon in s.s Pieter Faure samples).