Diagnostic characters
Shell minute, glossy, semitransparent, with short, blunt spire; whorls apparently smooth and tumid, sutures deep. Aperture rounded, narrower adapically, its edge everted basally and over a groove leading to a small umbilicus. Pale horn-colour with reddish brown markings, often in spiral rows.
Other characters
The four whorls may sometimes bear a few delicate spiral lines and some prosocline growth lines. The apical angle is 55-60°. The colour pattern varies: on the last whorl there is often a series of subsutural streaks and two peripheral rows of spots plus a basal row (sometimes absent); or the streaks may be interrupted to give two rows of spots (making 5 in all); or the spots may fuse to give chevron-like markings. The apex may be lilac. Up to 1.25 mm high, 0.8 mm broad; last whorl occupies about three quarters of shell height, aperture about half.
The animal is without pallial tentacles; the single metapodial one is long. White with yellow spots, metapodial lobes darker.
S. pulcherrima is a southern species which seems to reach its northern limit in the Channel Islands where it lives in tufts of fine weeds at L.W.S.T. Little is known of the breeding of these animals except that they produce hemispherical transparent capsules measuring about 800 µm across. Each contains a few eggs (3-9) which develop to young snails before hatching.