Retusa minutissima
Habitat: it lives in the infralittoral zone. It is often found into gastral cavities of Astropecten auranciacus.
Distribution: it can be found in a large part of the Mediterranean. Locally common. It is found plentifully into dredgings inside dykes of Leghorn port.
Notes: it is a characteristic shell due to its quite reduced sizes. Outline cylindrical and uniform all over its whole height. There can be rarely noted significant narrowings on last whorl. H/L ratio is particularly low. Sculpture is made by fine axial striae inclined, spiral sculpture missing. Apical zone usually flat-sided but there can be rarely, found specimens with apex protuding from last whorl (Oliverio and Tringali, 2001). Numerous striae helicoidal and irregular are visible in apical zone. It is recognizable from R. desgenettii (Audouin, 1826) presenting a quite evident axial and spiral sculpture due to a slight narrowing in median part of spiral and to an enlargment in the lower part. Average measures of adult specimens reach 1.2 mm in height.