A coral-strome reef developed in three stages:
Pioneer Stage: Branching corals colonized a suitable area of subtidal seafloor.
Intermediate Stage: Domed and platy corals built mounds in the middle of the widening reef.
Mature Stage—as the reef continued to widen:
Encrusting stromatoporoids and calcareous algae formed a durable protective ridge on the seaward side.
Tabulate and colonial rugose corals grew within quiet central lagoons.
Image courtesy of NOAA.
◄ Cross section of modern
Gray’s Reef, located off of Sapelo Island, Georgia.