Shell globose, up to 32 x 24 mm. Colour brown to almost white: spire coloured; last whorl with a broad coloured band covering the posterior half, and a narrow band near the siphonal fasciole but separated from it by a well marked depression.
Protoconch naticoid, multispiral with 3-3 1/4 whorls, dimensions and sculpture as in B. cancellata. Transition to teleoconch clearly marked. On the first half of teleoconch whorl, there are 5-8 narrow, close-set spiral ridges; axials are only very slightly indicated (difference from B. cancellata). Teleoconch with up to 5 3/8 rounded whorls. Sculpture consists of rounded axial ribs crossed by narrow spiral cords. Number of axials: on the first teleoconch whorl this is very difficult to count because they are very vague; 9-12, 10-11, 10-14, 11-16 on second to fifth teleconch whorls respectively; number of spirals: 5-8, 5-7, 5-6, 5-6 and 4-6 on first to 5th whorl. Width of spiral: increasing with age from 0.1 to 0.3 mm. From the 4th whorl on, one spiral of second order can occur between the main spirals, and often third order spirals can be seen. Between these macro-spirals, a set of very fine close-set micro-spiral lines can be seen on uneroded shells. An additional axial sculpture of growth-lines is present between the main rounded axials: fine growth-lines, often coarser than in B. cancellata, and crossing over also the secondary and ternary spiral cords, thus giving them a slightly rugose look. Aperture grossly semicircular, white. Outer lip slightly crenulate, 9-11 lirae within. "Stromboid notch" only slightly indicated. Columellar callus and folds as in B. cancellata, but sometimes a minor fourth fold occurs at the rim of the siphonal canal. Siphonal canal shorter than in B. cancellata', siphonal fasciole well developed but normally without showing the former siphonal canal. Umbilical chink generally slightly wider than in B. cancellata.

The shell of B. similis is rather similar to that of B. cancellata-, it is distinguished from the latter by its less-shouldered whorls, and its smoother and less coarse macrosculpture: axial ribs less pronounced, a finer and more elaborate spiral sculpture: between the main spiral cords, second order (as in the lecto-type) and third order spirals can be seen on shells in pristine condition (Fig. 2IB); these are lacking on B. cancellata. The spiral bands in B. cancellata are more pronounced than in B. similis. Both species cannot be distinguished on size and shape data only: their height/width correlation lines (with r2 = 0.98, p < 0.005) overlap almost perfectly, but B. cancellata appears to grow larger than B. similis

Specimens in collections range from the southwestern Mediterranean (Alboran Sea; Oran; eastern Spain: off San Carlos de la Rapita) to Namibia and South Africa, including Canary and Cape Verde Islands, but not Madeira. Bathymetry: from intertidal to 280 m.