The solid axial ribs (8-9 on the last whorl), a little bit undulated, and the very thickened external lip are characteristics of this species. There are also fine spiral incisions all over the shell. The colour pattern is rather variable, from light yellow up to reddish brown; sometimes, on a light ground, there are pinkish spots. The average measures are about 10 mm. H. secalina (Philippi, 1844), which has got a bigger number of axial ribs, is considered a synonym of septangularis, as well as H. rigida (Reeve, 1846) which has a less slim aspect and more angulated ribs.

Distribution: all over the Mediterranean but never common.
Habitat: it prefers detrital-muddy bottoms from a few metres depth (-10 m depth, port of Leghorn - Tuscany - Italy, on Caulerpa prolifera) up to bigger depths. It was found living even into Astropecten aurantiacus gastral cavities.