Halimeda Reef Algae growing between coral heads on slope

The coral reef is a very fragile part of the ocean, and many creatures are needed to help keep it healthy and in balance. Turf algae, coralline algae and halimeda algae, three groups usually present on most reefs, but their relative abundances can be a good indicator of the health of the reef.
 
The stealthy pink coralline algae cements coral reefs together, and strengthens and enriches the coral reef habitat. These pink stony crusts are found in sunlit parts of the seafloor.
 
Halimeda, a calcareous green algae, is an important, fast growing primary producer associated with coral reefs. They grow in shallow depressions, cracks and crevices, between hard corals and other somewhat protected areas of the reef.
 
Pink Crustose Coralline Algae
Scientific Name: Corallinales
 
Watercress Alga
Scientific Name: Halimeda opuntia