Star Coral - green

This beautiful stony coral seems to be a green type of Star Coral, genus Orbicella, most likely Orbicella annularis (Boulder star coral). Although stony corals are the most common reef builders, and there are plenty of brown colored ones on Rainbow reef, this was the only coral of this great deep green hue we saw during our dive.

As many corals, star corals are listed as endangered species One Zoom link to the genus Orbicella in the Tree of Life, although in Florida they seem abundant

A video of the whole formation (apologies for the shaky and shadowy image)

Orbicella corals typically grow in boulders and domes (therefore the common name of Boulder or Moutain star corals), but occasionally you find them in sheets, as in our case: with some small protuberances, but mainly laying flat around the surface of the rocks beneath it.

It seems it is difficult to single out one species from the genus. Until recently, they were considered a single species (Montastraea), and you can still find it named as such in many places. In 1992, with molecular characterization techniques, it was found to be three separate species, and the genus reassigned to Orbicella

 

Sea Fan

The Common Sea Fan (Gorgonia ventalina) stands majestic waving at the currents. This coral is easy to identify due to its shape. There are other close varieties in the family, but aparently they are found less frequently in the Miami reefs. Also found it named Purple Sea fan

This short video shows the waving movement

Purple Sponge

This beautiful sponge shines in the reef due to its purple color and distinct shape. 

I believe it belongs to the Callyspongia family, but have not been able to identify it to the species level.