A highly polished Turban sea shell. Turbans are the shells of the marine gastropods also known as sea snails.
The shell of a spiny Sea Urchin, possibly Stomopneustes variolaris, family Stomopneustidae. Black and white macro.
Black and white macro photograph of the shell of the channeled whelk (Busycotypus canaliculatus), family Busyconidae, about 3 inches.