When tourists flock to Okinawa’s southern Yaeyama Islands during the summer, one of the most popular and coveted souvenirs they can pick up is a bottle of hoshizuna—literally, star sand. Small vials and bottles packed with star-shaped grains backed by garishly colored sand can be purchased from omiyage vendors on Ishigaki and Iriomote Islands, while the more adventurous can collecttheir own on a secluded beach on nearby Taketomi. Of course, the tiny treasures are misnomers, and each “grain” of sand isn’t really sand at all. Instead, these spherical bodies with spike-like protrusions are actually the exoskeletons of foraminifers—marine protozoa that once lived on the ocean floor.

A common folktale on Taketomi Island asserts that long ago, the North Star and the Southern Cross decided to bring life to Earth. When she felt prepared for birthing, the Southern Cross asked God where she should have her babies. Surveying the Earth below him, God pointed to tiny Taketomi-jima and told her to go to the south side of Taketomi, where the current was warm and slow. Southern Cross descended upon the island and gave birth many times in the nearby waters.

However, the seven dragon god of the sea soon became angry because Southern Cross did not consult with him or as his permission before giving birth in his ocean. Filled with wrath, he called upon a giant serpent to kill all of the babies. The giant snake did as he was told, and swallowed all the tiny star babies and spat their bodies back into the ocean. One by one, they washed up on the shores of Taketomi and transformed into star-shaped grains of sand.

In a nearby village on the island lived a kind goddess, who, when she found the dead babies, gathered them up. She placed them in her incense burner, and when the villagers came to worship her during a festival, the particles turned to smoke and billowed into the sky and the waiting arms of the Southern Cross. Their tiny bodies can be seen around her in the sky.

To this day, when the annual festival is held at Taketomi’s southern beach, the villagers stoke their incense burners with star sand.

Want a bit of star sand but can’t make it to Yaeyama? Several omiyage stores on Kokusai hawk vials of hoshizuna for as little as ¥100.