This is formed by a rocklike accumulation of calcareous skeletons
They are often very 
slow growing, and may occur on rock, coral skeletons, shells, other algae or 
seagrasses... [DOC] [TLE] Essay Writing Service - Investigation of Coral Reefs :: Papers [PAR] It is formed by a rocklike accumulation of calcareous (calcium-containing) 
exoskeletons of coral animals, calcareous red algae, and molluscs.