Small, depressed cone-shaped shell with angular periphery, shallow suture, moderately wide umbilicus, and sculpture consisting of rounded tubercles; upper-side sculpture with 4 ribs (uppermost coarsest), plus a finer one before the keel-forming ribs; prominent angular double keel formed by 2 almost equally developed ribs, with 1 narrow rib centered between them; basal sculpture of 7-8 spiral ribs, innermost (surrounding umbilicus) broadest and with 8-10 large, regular nodules; umbilical side of columellar wall without spiral sculpture or with weak spiral projection in large shells. Tan, with midrib and basal areas darkest, subsutural rib and periphery white with pattern of orange-tan blotches. Protoconch diameter 0.86-0.94 mm, distinctly heterostrophic, without anal keel.
Teleoconch: small, diameter of known specimens 6.3-9.7 at 3 1/4-4 1/8 whorls. Shape: depressed cone-shaped with angular periphery; moderately wide umbilicus (UD ca. 15% of SD); suture shallow. Sculpture: consisting of rounded tubercles; Upper side: SSR with coarser granules than following 2 MR; MR and ± equally strong UPR with smooth and flattened nodules; between UPR and keel-forming LPR with 1 narrow additional rib; angular periphery formed by almost equally prominent LPR and IPR, with 1 narrow additional rib centered between them; upper point of whorl attachment at LPR, hence no distinct suture; base with 7-8 spiral ribs, increasing in width towards umbilicus; innermost (UC) broadest and with 8-10 large, regular nodules; umbilical side of columellar wall without distinct spiral sculpture, or, especially in larger specimens, with 1 indistinct ridge not bearing nodules; inner lip strong. Coloration: shades of tan with MR and basal areas darkest; SSR and PR white with pattern of narrow (1-2 nodules wide) orange-tan blotches, the latter often extending as darker flames onto both sides; ribs surrounding umbilicus (UC and PUR) white; grooves between spiral ribs, especially on base, darker. - Protoconch: small to medium-sized (0.86-0.94, x = 0.90), multispiral, distinctly heterostrophic, folds visible in false umbilicus; without anal keel; tan, darker towards peritreme . - Operculum as described for subgenus, with height equal to diameter. - Radula and Anatomy: not known.

Heliacus geminus is similar to the narrowly-umbilicated morph ("africanus-form") of H implexus. However, that form lacks the additional rib between upper peripheral rib (UPR) and keel-forming lower peripheral rib (LPR), possesses a distinctly nodulose spiral rib on the umbilical wall, and has a protoconch larger than 0.94 mm. Heliacus cerdaleus has a similarly angular periphery and narrow umbilicus surrounded by coarse nodules. Members of that species have only one midrib and the protoconch is smaller than 0.80 mm. See also H enoshimensis.

Geographical distribution: Known only from New Caledonia and the Andaman Islands.