“Star sand” that is commonly found on Okinawan beaches is a marine sediment made of tiny, star-shaped shells produced by protests called foraminifera.

When foramina die, the shells remain in the sea and are carried to the shore by the tides. The star-shaped shells are created specifically by a species called baculogypsina, which are quite rare as a rule, but on the reef-fringed islands of Taketomi and Iriomote, they have created whole beaches sprinkled with star sand.

The star sand is commonly sold in small bottles as popular souvenirs.