Large cone-shaped shell with widely open umbilicus; whorls on upper side gemmate, somewhat inflated; two spiral grooves below suture (midrib-area divided subequally, with the upper midrib narrower); groove at the base of lower midrib. Subsutural rib white with pattern of + large reddish-brown blotches extending onto upper midrib; most specimens with reddish-brown axial flames on basal field; proxumbical rib pure white; umbilical crenae reddish-brown (white on body whorl of larger specimens). Protoconch diameter < 1.26 mm.

Teleoconch: Large, diameter of specimens in collections usually 25-35 at 6 to 7 1/2 whorls. Shape: moderately depressed to fairly high-spired cone-shaped, with whorls somewhat inflated (especially on upper side); umbilicus wide (UD ca. 26% of SD). Sculpture: Upper side: SSR distinctly separated; LMR wider than UMR (ca. 2:1, later 3:1); groove at the base of LMR; Periphery: PR strong, with UPR almost as prominent as LPR; upper point of whorl attachment on upper edge of LPR (thereby covering it; suture narrow); upper side and periphery crossed by deeply incised oblique axial grooves, resulting in formation of many elongate oblique segments, becoming smooth on MR-area of body whorl of larger specimens; segments of the two MR not necessarily corresponding; Base: IPR strong; always one additional narrow spiral rib between LPR and IPR; BF without spiral ribs; with radiating plications (especially in younger specimens), stronger towards umbilicus; two distinctly separated nodulose spiral ribs (PUR and UC) surrounding umbilicus, with umbilical crenae very regular; columellar wall forming almost straight inner lip with plications for support of the columellar muscle, with deepest groove in umbilical crenae overhanging umbilicus; no spiral sculpture on umbilical wall. Coloration: SSR initially white, with pattern of reddish-brown blotches (ca. 6-9 per whorl, each 2-4 nodules wide), starting at about 3 Tw; UMR initially purplish-brown, turning tan as LMR after about 2 Tw; beginning with 4th whorl, blotches of SSR extend onto UMR; UPR, LPR and IPR whitish with reddish-brown blotches (each about 2-4 nodules wide); BF marbled in mauve and tan, often with large reddish-brown flames extending from IPR; one spiral band of small brown blotches in front of PUR; PUR pure white; UC reddish-brown, turning white on body whorl of large specimens. - Protoconch: medium-sized to large (1.02-1.26, x = 1.13); distinctly heterostrophic; without anal keel; yellowish-white with brown outer corner in front of varix. - Operculum: as described for genus. - Radula and Anatomy: not known.

Shells of Architectonica purpurata resemble those of A. maxima in sculptural features, especially in having a similar subequal division of the midrib-area. The shell, however, is much smaller in size, has a narrower umbilicus, a smaller protoconch, and can be readily separated by the color pattern of large blotches that extend onto the upper midrib, and by the combination of reddish-brown umbilical crenae with a pure-white proxumbical rib. A. stellata is similar.

Northern Indian Ocean to New Guinea in the western Pacific. Records from eastern Indian Ocean and from Hawaiian Islands in need of verification.
Habitat: Sublittoral (no depth records available).