Curaçao
The cave star coral, Madracis pharensis, lives in the darker corners of coral reefs. Most corals have an obligate symbiotic relationship with dinoflagellate algae, Symbiodinium. But M. pharensis can form colonies with or without Symbiodinium. This colony was photographed under a deep overhang off the Caribbean island of Curaçao during field work to study the diversity of coral symbionts. Corals that lack Symbiodinium proved to be a rich sources of previously overlooked symbiotic relationships.