Shell hyaline, biconic, fusiform and 1.8 times as long as wide. Its multispiral protoconch has its nucleus chipped off, is approximately 440 µm wide and consists of almost 2.60 diagonally cancellated and convex whorls the last of which with a weak keel before the onset of the teleoconch. The teleoconch consists of 4 convex whorls separated by a deep suture and exhibiting a conspicuously strong shoulder. The body whorl occupies almost 70% of the total length and bears 12-13 orthocline axial ribs with interspaces approximately equal in width to the ribs and 17 thin spiral cords, 5 of which are situated above the aperture and the rest 12 bellow. The spiral cords in their intersections with the axial ribs form erasures in the form of small elongated rectangular tubercles. The tubercles on the first 2 adapical cords are spiny forming a strong subsutural ramp. The inner wall of the shell viewed through the aperture exhibits a transparency. Aperture wide, occupies approximately 50% of the shell length and exhibits a rough and sigmoid columella, angled at its upper part. The anterior siphonal canal is long and wide while the posterior one is short. Color uniformly cream-white with a light brown subsutural band by the ramp and a wider one as an extention of the suture on the body whorl. Protoconch also light brown. Teleoconch covered all over its surface with small erasures.

R. brunneofasciata superficially resembles R. echinata (Brocchi, 1814) in its spicky outlook, but is much more inflated than the latter and is covered all over its surface with small erasures.

Mixed bottom with Posidonia oceanica. Known from the Ibiza region.