Small to medium-sized, depressed to rounded cone-shaped shell with very narrow to wide umbilicus; upper-side sculpture of 3 almost-identical ribs with more or less flattened nodules; rounded double keel formed by 2 almost-identical ribs; basal sculpture of 5 very regular spiral ribs; umbilical side of columellar wall with 1 strong spiral rib. Bluish white with pattern of brown to near-black flames, increasing in size with number of whorls; parietal region usually brownish. Protoconch diameter 0.76-0.88 mm, distinctly heterostrophic, without anal keel.
Teleoconch: small to medium-sized, diameter of specimens in collections usually 7-13 at 3 1/3 to 4 2/3 whorls (rarely more than 15 at 5 1/2 whorls). Shape; from depressed cone-shaped with wide umbilicus to rounded cone-shaped with very narrow umbilicus (UD 8-31% of SD, x = 17.5). Sculpture: Upper side: SSR, single MR and UPR almost identical, with ± flattened nodules; Periphery: rounded double keel formed by almost identical LPR and IPR, rarely (in large specimens) with 1 additional, much finer rib between them; upper point of whorl attachment between LPR and IPR, suture shallow; Base: 5 very regular spiral ribs, somewhat increasing in width towards umbilicus, innermost forming UC; UC with 9-24 nodules on body whorl; umbilical side of columellar wall with 1 strong spiral rib. Coloration: bluish white with pattern of near-black flames (fading to brown after death); especially peripheral ribs with lively brown-black/white pattern; size of dark flames increasing with whorls, therefore number per whorl almost constant in specimen; grooves between spiral ribs orange-brown; UC usually white, parietal region usually brownish. - Protoconch: small (0.76-0.88, x = 0.83), multispiral, distinctly heterostrophic, without anal keel; bicolored, with area before peritreme dark brown to black and remainder glassy white; if dark area does not cover highest point of apex, with 1 brown fleck. - Operculum: as described for subgenus. - Radula: five-toothed taenioglossate (2-1-2); rachidian tooth stronger than marginal teeth, with prominent, pointed median cusp flanked by more than 20 smaller, blunt cusps; marginal teeth longer, curved and forked, inner marginals with 9-10, outer with 10-13 tapering cusps. - Anatomy: described by HASZPRUNAR (1985b). - Soft-body coloration of living animal: body color milky to orange-white, tentacles and upper side of foot ± strongly speckled with black pigment (in larger animals tentacle tips and anterior margin of foot without black pigment); embedded white granules loosely distributed, including anterior foot margin; sole of foot with thin layer of black chromatophores, resulting in light-grey coloration (pers. obs., South Africa; see also HASZPRUNAR, 1985b: figs. 13-15).

(Synonym: Torinia variegata depressa Philippi, Edmondson, 1933.) Height, 9 mm; diameter, 12 mm. Shell: turbinate or depressed, solid; variegated brown or black and white. Spire: four inflated whorls; suture barely distinguishable. Sculpture: four coarsely beaded cords, those marking the periphery of each whorl of larger and more convex beads. Aperture: subquadrate, marked by the spiral cords of the periphery. Base: umbilicus narrow and deep, bordered by a crenulate spiral. Color: brown or black, spotted with white; base around umbilicus white. H. variegatus is the most common of the architectonicids in Hawaiian waters. The animals are associated with sea anemones of the genus Palythoa to which they are attached by a thin mucous thread.
This species occurs throughout the Indo-West Pacific, from the Seychelles and Ceylon to the Marquesas Islands.

Heliacus variegatus is the most common intertidal species of this family in the Indo-Pacific. It shows a high intraspecific variability, similar to the range of variation displayed by H. implexus (MIGHELS, 1845) (see below). Within one population specimens can be found with very narrow or very wide umbilici, with very depressed or relatively high-spired shells (see Figs. 154-156). As a result, several forms have been described and named as "variations,* "forms”, subspecies or even nominal species. The discussion usually focussed upon the interpretation of the figures in CHEMNITZ'S 'Conchylien-Cabinet' (1781: pl.173 figs.1708-1709 and 1710-1711) which GMELIN (1791: 3575) cited in his description of the two nominal species Trochus variegatus and Trochus areola, respectively. According to GARRARD (1977: 540), these are members of the same polymorphic species and display within one population "every possible intergrade in colour pattern." This is not the case. Studies by the present author on South African populations of these forms, as well as comparative analyses of collection material from many localities throughout the Indo-Pacific, revealed two sympatric morphs that were always distinguishable by several characters. These two morphs are here interpreted as two species, Heliacus variegatus (GMELIN, 1791) and Heliacus areola (GMELIN, 1791). They differ in protoconch size (Fig.157) and in the coloration of the subsutural, infraperipheral and parietal ribs (usually white in H. areola). Other characters to distinguish the two are the number, shape and size of the color flecks on the peripheral ribs (counted on body whorl of specimens with more than 3 1/4 teleoconch whorls): in H. variegatus the number of the flecks on the peripheral ribs of the body whorl ranges from 6 to 16 (x = 10, n = 476; flecks extending as flames), in H. areola this ranges from 10 to 23 (x = 15, n = 68; flecks small and well-defined). In H. areola the subsutural rib is the lightest colored part of the teleoconch upper-side and periphery, in H variegatus it is the lower peripheral rib. In H variegatus the shell-shape varies from depressed to rounded cone-shaped, in H. areola it is always rounded cone-shaped.
Heliacus variegatus is often confused with H (Torinista) implexus (MIGHELS, 1845) [= dorsuosus auct; see below] and with H. (T) sterkii PILSBRY & VANATTA, 1908. Members of those species, however, have two midribs, resulting in a total of five, not four, ribs visible on the upper side of the shell.

Geographical distribution: Continuous range from the African east coast to central Pacific.
Habitat: Lives near or between polyps of intertidal and upper subtidal zoanthinarian colonies.
Habits/feeding behavior: Feeds on zoanthinarian polyps (various species of zoanthid genera Palythoa and Zoanthus; see also ROBERTSON, 1967: 246). In exposed environments at the South African Natal and Transkei coasts, it prefers Palythoa nelliae PAX, 1935. This preference appears to be based on physical constraints (relation of shell size/polyp size; pers. obs.).