Symbiotic algae

Symbiotic algae

tiny spheres of sympiotic algae

Because they are tiny round spheres with few features to tell them apart, the symbiotic microscopic algae of corals were once thought to be a single species found in all reef-building corals. These symbionts are now recognized to be a group that comprises hundreds and possibly thousands of species that can be sorted into at least 15 genera.

Image: Todd LaJeunesse