Tectura persona (masked limpet)

Found on the large rocks in area 3 until the storm changed the beach in the 90’s. By mid-1990’s there were few left (in a day you could find 10). By the summer of 1996 you had to wait until dusk and then only two were visible.

If the shell is dark brown and looks a bit like tree bark and the inside is dark colored at the apex, it’s probably Tectura persona, the masked limpet.