The prograding shallow component ends with an abrupt drop-off at 55 meters depth. The deep forereef cliff then continues vertically to approximately 122 meters below sea level. The latter are sparsely colonized due to high sedimentation rates. Agaricia and Montastrea cavernosa and the calcareous green algae Halimeda . As light penetration diminishes with depth, these corals grow upward and outward and forms tend to be flattened to increase the amount of surface area exposed to light.
Corals tilt seaward, preventing sediment accumulation on flat coral surfaces.
In July 1970, a team of scientists used explosives in the deep forereef and recovered the resulting reef talus, including the sample used in this study. The sample is characteristic of the deep forereef. Three layers of Agaricia plates are obvious though it is unclear if more than one colony is present. Lateral bands indicate growth direction. Encrusting sponges are obvious on the exterior, as are the effects of two boring sponges.