Found on the beaches of Okinawa, Japan, and across the south and west Pacific, this special sand is very rare. “In Okinawa, some islands like Taketomi, Hatoma and Iriomote are famous for finding star sand,” says Fujita, “but it is difficult to find in other islands.”
Photosynthetic stars
These tiny organisms have a special companion. “They have these little photosynthetic algal cells, called diatoms, that live inside the skeleton,” says Wilson.
The diatoms take in light and produce carbohydrates and oxygen.
“So the individual bit of star sand—the individual skeleton—is actually a little community of the one big cell, the foraminifera, and all these tiny other cells that live within it,” he says.
The animal’s star-shaped body has tiny threads that help channel light to the diatoms so they can make food. The star has little projections radiating out from the center of the grain of sand, like the spokes of a wheel. “If you look at the tip of the projections, it’s almost clear. Light shines through these channels inside the cell, and the diatoms live in those channels,” says Wilson. “It’s like fiber optics on the inside.”
AloJapan.com