SHELL. Very large (up to 190 mm in length, average length about 150 mm), with seven inflated teleoconch whorls. Protoconch of about two and one-half angulate volutions, ending in small, straight varix.
Spiral ornamentation on first teleoconch whorl of two or three weak cords masked by axial ribs, continuing very weakly on succeeding whorls. On third whorl, two minor cords appearing on subsutural ramp and another between each pair of major cords. Body whorl with four very low and flattened major spiral cords, each separated by two or three exceedingly weak spiral threads. Spiral ornamentation on siphonal canal visible only where drawn out into spines.
Axial ornamentation on first teleoconch whorl of nine ribs, angulate at shoulder; on second whorl, every third rib strengthened into varix with short, stout, apically recurved spine at shoulder; intervarical ribs rounded ridges. By fourth whorl, intervarical ribs completely lost and succeeding whorls ornamented solely by weak spiral threads. Three low, narrow varices per whorl, bearing stout spines, spines at shoulder and periphery apically recurved, anterior ones more adaperturally directed; three primary spines on varices on body whorl, one secondary between that at periphery and base, another at juncture of base and canal; some specimens with single adaperturally-directed small spine between shoulder and peripheral spines. Siphonal canal with five or six long, stout, adaperturally-recurved spines, decreasing in length anteriorly, posterior-most longest. Secondary spines alternating with primary spines, approximately half as long and bent adaperturally at increasingly greater angle to primary spines; posterior-most spine almost parallel and anterior-most at angle of 90°.
Suture impressed, crossed diagonally by lamellate growth lines, posterior ends of lamellae directed adaperturally.
Aperture elongate-oval; outer lip deeply notched by median groove of spines, size of notches corresponding to strength of spines. Tooth-like projections separated by notches in advance of varix; projection posterior to spine at base of body whorl elongated to form large labral tooth. Prominent anal notch at posterior end of aperture between projecting end of subsutural ramp and thin appressed end of inner lip; edge of subsutural ramp extending above suture reaching almost to shoulder of preceding whorl. Anterior two-thirds of inner lip free-standing, narrow, smooth. Siphonal canal long; terminations of previous canals fused into tube, open by narrow slit; spinose for almost entire length.
Colour creamy white with major spiral cords coloured golden brown on tops but not extending on to spines; often a darker blotch on subsutural area mid-way between varices; aperture white, interior light brown with slightly darker brown lines corresponding to spiral ornamentation.
Operculum brown; subterminal nucleus, with eight to ten strong concentric ridges, angulate at line extending along length.

The shell of the Persian Gulf form differs from shells of typical Red Sea specimens in usually having a longer, more adapically directed shoulder spine and a secondary spine is usually developed between the shoulder spine and the spine below. In addition, the inner lip is less expanded over the parietal wall. The protoconch of most Persian Gulf specimens lacks a keel and the axial colour lines are usually better developed. None of these characters are, however, consistent and we do not think that subspecific status for the Persian Gulf populations is warranted.
Shells of deep-water specimens tend to develop longer, more slender spines than shallow-water specimens.

This species is confined to the Red Sea and Persian Gulf.