Large to very large, moderately depressed cone-shaped shell with widely open umbilicus; whorls on upper side gemmate, somewhat inflated; two spiral grooves below suture (midrib-area equally divided); narrow groove at base of lower midrib. Subsu¬tural rib white with pattern of brown blotches; midribs uniformly greyish-brown; basal field with 1-3 dotted spiral lines; proxumbical rib whitish with few brown blotches; umbilical crenae pure white (rarely with single brown blotches). Protoconch diameter <1.18 mm.
Teleoconch: Large to very large, diameter of specimens in collections usually 30-45 (rarely to 55) at 7 to 8 (8 1/8) whorls. Shape: moderately depressed cone-shaped, with whorls somewhat inflated (especially on upper side); umbilicus wide (UD ca. 29% of SD). Sculpture: Upper side: SSR distinctly separated; MR-area initially almost undivided, separating into UMR and LMR (nearly 1:1) after about 2 Tw; narrow groove at base of LMR; Periphery: PR strong, with UPR almost as prominent as LPR; upper point of whorl attachment above center of LPR (after ca. 5 1/2 Tw at upper edge of LPR), thereby displaying part of LPR as element of upper-side sculpture; upper side and periphery crossed by deeply incised oblique axial grooves, resulting in a general gemmate appearance, becoming weaker on midrib-area of body whorl of larger specimens; Base: IPR strong; 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 UC strong; columellar wall forming almost straight inner lip with plications for support of the columellar muscle, with deepest groove in UC overhanging umbilicus; no spiral sculpture on umbilical side of wall. Coloration : SSR white with pattern of brown blotches (each about 1-2 nodules wide), starting after about 1 Tw; UMR-area initially mauve-grey, later greyish-brown as LMR-area; UPR, LPR and IPR white with brown blotches (each of which about 1-2 nodules wide), with LPR generally lighter colored than other ribs; BF flamed with mauve and tan, with 1-3 dotted spiral lines of varying width; PUR whitish with brown blotches; UC pure white (rarely with single brown blotches. - Protoconch: medium-sized (1.00-1.18, x = 1.06); distinctly heterostrophic; without anal keel; whitish, with brown outer corner in front of varix. - Operculum: as described for genus. - Radula and Anatomy: not known.

Architectonica grandiosa has been synonymized with A. maxima by most authors. It can, however, be easily distinguished by the midrib-area which is divided into two equally-strong spiral ribs, pure-white umbilical crenae, and a much smaller protoconch size. The coloration of the type specimen has faded; fresh specimens are much richer in contrast. Architectonica gualtierii n.sp. is similar (see discussion, below).

Geographical distribution: Apparently restricted to Australian region (other records in need of verification). Habitat: Sublittoral (most depth records between 45 and 125 m), live records from 45-65 m, sandy and muddy substrates.