Coral Reef Algae Have Eyes?

The single-celled algae that set up house inside hard corals and give reefs their vibrant colors may be able to see, a new study says. The algae—called zooxanthellae—have mysterious crystal-like deposits, which were found to be made of uric acid, a common element in light-reflecting structures in insect and animal eyes.

The substance in the algae had been previously misidentified as calcium oxalate, which is often found in plants, the researchers say.

The algae's crystal clusters strongly reflected light in lab experiments, suggesting that "this is really a functional eye," study co-author Kazuhiko Koike, of Japan's Hiroshima University, said in an email.

Each of the single-celled orgamisms also contains a photoreceptor molecule, which creates an "eyespot."