sentences:  Traditionally, the shells of "Antalis pretiosum" (previously known as "Dentalium pretiosum", the precious dentalium (a species which occurs from Alaska to Baja California) were harvested from deep waters around the Pacific Northwest coast of North America, especially off the coast of Vancouver Island.Today most dentalium shells in the shell trade are smaller, more brittle, and are harvested from coasts off Asia — i.e.they are shells of Indo-Pacific species of scaphopods.