Shell triangularly ovate, moderately stocky with a wide shoulder, attaining 46 + mm (holotype); spire extended; protoconch of 3,5 smooth whorls, erect and papillate; 5+ postnuclear whorls cancellated, with 10 moderately weak spiral cords, crossed by 10 conspicuous, spinose axial ridges (varices) per whorl; juncture of spiral cords and varices with a sharp, hooked spine; spines most prominent at the shoulder; intervarical areas with 8 to 10 evenly spaced axial lamellae; parietal shield large with outer margin raised and covered with numerous pustules; parietal pustules linear near the aperture, pimplelike on the outer margin; outer lip thickened, crenulated and toothed; 9 primary teeth form linear bifid projections on the inner labial margin, secondary teeth confined to postmarginal surface; anal sulcus shallow; siphonal canal short, recurved, open.
Color-Nucleus shiny, light-tan; postnuclear whorls with whitish base color, overlaid with flecks of reddish brown; 4 widely interrupted brownish spiral bands on body whorl (1 band on shoulder, 2 on either side of midbody area, 1 near the base); darkest coloration of bands on side facing apertural face of each varical spine and on edge of outer lip; bands more defused in Paratype B; parietal shield glazed, buff color with posterior surface tinged a pale lavender-white; pustules white; outer lip glazed, buff color with dark-brown blotches (4 major blotches formed at labial base of spiral bands and 2 secondary blotches between each spiral band).
Type locality - Davao Gulf, Mindanao Island, Philippines, netted in 200 meters in 1980 by Filipino shell fishermen.
Distribution - Known only from Davao Gulf and Bohol Strait.
Etymology-Named for Joel Greene, an avid collector and a purveyor of shells.
Remarks -This species is reminiscent of the western Atlantic species Morum (Oniscidia) dennisoni (Reeve, 1842; Dance and Emerson, 1967, p. 93-94, pi. 12, figs. 5-7), but differs in details of the sculptural ornamentation and in the coloration of the aperture and parietal shield. Morum (O.) exquisitum (Adams and Reeve, 1848), a species also known only from Philippine waters (Emerson, 1977, p. 83, 84. figs. E, F, J), has a more robust shell, with stronger and more numerous axial ribs, and a purplish pink parietal shield and outer lip. Morum (O.) kurzi Petuch (1979, p. 7, figs. 10-13), recently described from the Philippine Islands, has a smaller shell with coarser sculpture and an orange-colored parietal shield and outer lip. The Sino-Japanese species, M. (O.) macandrewi (Sowerby, III, 1889; Habe, 1964, p. 67, pl. 20, fig. 4), has coarser sculpture, stronger banding, with a white parietal shield and a white outer lip bordered with numerous dark blotches on the outer labial rim.