Turbinidae

Turbinidae, the turban snails, are a family of small to large marine gastropod molluscs in the superfamily Trochoidea.

==Description== Turbinidae have a strong, thick calcareous operculum readily distinguishing them from the somewhat similar Trochidae or top snails, which have a corneous operculum. This strong operculum serves as a passive defensive structure against predators that try to enter by way of the aperture or that would break the shell at the outer lip. These operculum are rounded ovals that are flat with a swirl design on one side and domed on the other. They are known as Pacific cat's eye or Shiva eye shells or mermaid money, and are used for decorative purposes.