Perhaps the most important property of coral structure is the coral rampart that goes up to right beneath the surface of the water. The coral rampart is composed of rounded coral heads and strong branching coral. Coral rampart frame are smaller, more fragile corals, and red and green calcareous algae. Although the algae have a small biomass, their high turnover rate is so high that the sand that makes their skeletal remains is the majority of calcium carbonate deposited.

Fish and invertebrates live and hide in the coral cracks, while sessile animals live on undersides of corals. A reef’s crest runs parallel to the coast, sometimes as close as up to the shore. The reef can also makes lagoons 5 meters deep, sandy, and a few hundred meters wide. The reefs are isolated from waves and speckled with coral heads. The lagoon contains many patches of calcareous algae and bottom-living animals like sea urchins, and sea cucumbers. The bottom-living animals actually filter organic matter out of the sediment. There are dense lawns of the sea grass Thalassia that are habitats of sea urchins, conchs and others.

On the seaside of the corals are the fore reef where corals blanket the sea floor. The corals form buttresses divided by narrow, sandy channels through which flow fine sediment flows. The channels can be 10 meters deep and are roofed with corals. These channel pathways are necessary because the coral reef would suffocate otherwise. Down away from the buttress zone is a coral terrace. From there, there is a slope of sand with coral pinnacles, then another terrace, and finally a vertical wall dropping off.

In nature, coral species are distributed by depth. Very few algae or symbiotic corals grow well past 100 meters because of the lack of light. As a matter of fact, the animals that live past 100 meteres mostly feed off of the detritus from above. Detritus feeders include true sponges, antipatharians (“precious corals”) and gorgonians (sea fans). Also, there are sclerosponges. Sclerosponges are an ancient group of major reef builders which were once believed extinct, but have been found in Jamaica living at a lower water level. The reason for the lower water level appears to be because faster-growing corals displaced the Sclerosponges, forfeiting in Darwin’s “survival of the fittest.” (Darwin’s theory of evolution stated that species suited for their environment will continue to thrive and may even displace species less suited for their environment, hence the name, survival of the fittest.)