Trochus is a genus of medium-sized to very large sea snails. They are marine gastropod molluscs in the family Trochidae, the top snails.
Trochus niloticus, for example, is a very large (up to 13 cm) Indo-Pacific top shell, which has a very thick inner layer of nacre. This species is commercially exploited to make mother of pearl buttons, mother of pearl beads, pendants and so on.
Sea snails in the genus Trochus
have shells that have a conical spire
and a flat base.