Shells small, « generally oval in shape, without epidermis, most often marked with punctate streaks or formed with dimples in transverse lines. Spire short, sometimes entirely wrapped. Aperture entire or notched anteriorly; labrum simple, sharp, or reflected and thickened outside, sometimes toothed. Columella almost always provided with more or less numerous large folds. » – A. D. d’Orbigny: Paléontologie française. Description zoologique et géologique de tous les animaux Mollusques et Rayonnés fossiles de France. Terrains crétacés vol.2, Paris 1842, p.106. Little is understood about the morphological distinction between the smallest species and genera.
 

Shell more or less globose, with rounded whorls, a marked suture, a weak to strong spiral sculpture, a body whorl exceeeding in heigh the two thirds of the total shell length; the aperture is extremely narrowed and angular posteriorly, ovate anteriorly; columella straight, folded in some species; columellar callus thin, restricted to the apertural area; no umbilicus. The operculum, which fits the aperture, is remarkable by its outline and its sculpture; nucleus anterior, subterminal.
 

« Shells fairly small (3-5 mm) with a more or less fragile appearance; outline ovate-conical, with a well-developed and slightly scalar spiral; protoconch heterostrophic, sunken and semiglobose, consisting of a paucispiral larval shell of 1.52 whorls; teleoconch formed by approximately 3-5 whorls with a clearly visible suture; external surface adorned with a microsculpture formed by spiral striae which under high magnification appear to be composed of small oval (C. thyrrenicum) or subquadrate (C. amabilis) pits placed side by side in a chain fashion; colour hyaline white; aperture subrhomboidal, narrower at the top; columella almost straight and bearing a modest median fold; lip thin, more or less crenulated. » – Repetto & Bianco: “Callostracon n. gen. (Gastropoda: Acteonidae): ratifica di “Callostracon” Nordsieck, 1972 nome non disponibile”, Bollettino Malacologico vol. 48(1), Milano 2012, p.40.
 

Shell devoid of particularities. The genus is mainly characterized by its anatomical features, starting with the structure of radula; it occurs in shallow as well as in deep water.