Shell small for genus, averaging only 17.5 mm, distinctly cone-shaped, with straight sides and flattened spire whorls; shoulder sharply-angled, bordered with 9-10 small, sharp knobs; body whorl ornamented with 8 large, evenly-spaced spiral cords, with cord around anterior end being largest best-developed; large spiral cords ornamented with 8-10 small, rounded beads, giving shell surface a pebbled appearance; areas between cords heavily ornamented with numerous fine raised spiral threads; parietal shield proportionally large, well-developed, adherent, extending over at least half of shell base; parietal shield covered with very numerous tiny rounded pustules; labrum thickened, smooth, with inner edge being lined by 18-20 small teeth; shell color yellow-white, covered with very numerous black dots, speckles, and small flammules, with largest and darkest flammules being on spire whorls; black flammules arranged in longitudinal rows and often encircle rounded beads on spiral cords; aperture and parietal shield white; protoconch pale yellow, projecting and mammilate, composed of 3 whorls.

Morum damasoi is the smallest of the known western Atlantic Morum species and is less than half the length of its Brazilian congener, M. berschaueri. This new species also differs from the other six western Atlantic species in being the only one that lacks the three or four rows of large knobs on the body whorl, having instead eight large beaded cords that encircle the shell. This character, along with the flat spire and sharply-edged shoulder, readily separate M. damasoi from any other known Morum species.

Type Material. HOLOTYPE length 17.5 mm, width 11.5 mm, 20 m depth off Coroa Vermelha, Abrolhos Platform, Brazil, MZSP 150893; OTHER MATERIAL EXAMINED - length 18 mm, width 12 mm, from the same locality and depth as the holotype, in the research collection of the senior author; length 18 mm, from the same locality and depth as the holotype, in the Damaso Monteiro collection.
Type Locality. 20 m depth in coral rubble, off Coroa Vermelha, Abrolhos Platform, southern Bahia State, Brazil.
Distribution. Known only from coral reef areas on the Abrolhos Platform off southern Bahia State, south central Brazil.