Shell solid, spiny in aspect, conic in outline, whorls convex, suture deep. Once large axial and spiral ribs cross they make some spines quite prominent. Over its mouth only two spiral cords are visible. Mouth roundish in form, lip thickened and varicose, spiny externally and denticulated internally. Columella large and callous. Embryonal whorls are large and obtuse since protoconch is paucispiral and lecitotrophic. Uniform white in colour. This species is really similar to A. cancellata that, besides being larger in sizes and being less slim in outline, it has a protoconch multispiral and planktotrophic, moreover it has always three spiral cords over its mouth instead of two and it presents a large nodule at the base of columella. Sometimes cancellata is yellowish in colour while hirta is constantly white. Average measures of adult specimens reach 3 mm in height.

Habitat: it lives in the infralittoral and circalittoral zones on solid substrata in the presence of algae. Distribution: it can be found all over the Mediterranean. More common in the southern sector.