Calliostoma scalenumCalliostoma scalenum, common name the Gulfstream top shell, is a species of sea snail, a marine gastropod mollusk in the family Calliostomatidae.DescriptionThe size of the shell varies between 14 mm and 41 mm.DistributionThis species occurs in the Gulf of Mexico and in the Atlantic Ocean off North Carolina, USA, at depths between 25 m and 80 m.