Bolma johnstoni is a stunning turbinid characterised by a well-developed, near-black basal callous which makes it unforgettable and unmistakeable. The shell surface carry scaly sculpture and a single row of rather long spines, the operculum is an attractive reddish-brown coloured one with a granulose central area. A famous endemic species of Angola, it is a rare species due to its restricted distribution and is much sought-after by collectors. It inhabits rather deep water around -70-120m, and although no reliable data exists regarding its detailed feeding behaviours it is almost certainly a grazer. Typical shell diameter including spines around 40mm., very large specimens may exceed 50mm. In the original description it was placed in the genus Astraea, and later moved to Bolma, its current genus. On dealers' lists and collection databases it is quite often misspelt as « Bolma johnsoni » (missing a « t » in the specific epithet).

DIAGNOSIS. Shell: Whorls convex, with scaly, nodular sculpture and moderately long peripheral spines. Peripheral angulation on lower 1/3 of spire whorls, somewhat rounded on last whorl. Twelve spines on body whorl. A second angle below periphery is rather indistinct on body whorl. Five coarsely squamose, oblique cords below, the lowest at the basal angulation. Five sparsely nodulose basal cords. Basal callus broad, extending over much of base, reddish brown, columella white. Surface light red.
Operculum: Quadrately oval, smooth and convex with granular central area; reddish-brown with white margins.
DIMENSIONS. Not known.
TYPE LOCALITY. Porto Alexander, Angola, 60 fathoms (110 m). HOLOTYPE. Natural History Museum, Stockholm.
OTHER LOCALITIES. Apart from the three specimens from the type locality, the only recorded specimens are two from off Orstom, Gulf of Guinea, in 85 m (Anon. 1972, p. 13).
Odhner (1923, p. 10) compared this species only with B. rugosa, but it is more similar to B. modesta and B. aureola than to B. rugosa. It differs from B. modesta in the more regularly squamose upper surface, in developing a single peripheral row (rather than two or three rows) of spines, and in the reddish brown (rather than white) operculum; and from B. aureola in its markedly smaller size (assuming Odhner's figure is natural size; he did not publish dimensions), the more widely spread basal callus, the lack of a spiral groove in the operculum and the markedly fewer rows of granules; and from both in its reddish-brown, rather than orange, basal callus.