Alikreukel (Turbo sarmaticus) or giant periwinkles are also called ollycrocks, cockles or turban shells. Like abalone, alikreukel are a slow-growing, heavily exploited food source and very large specimens are rare outside of marine reserves. They have a door to protect themselves with which can shut.
This amulet represents boundaries. The ability to shut one's door, as well as your right to Peace of Mind.