Corals are characterized their
polypoid shape, and slow
growth secretion of a skeleton
made of carbonate. Numerous
coral associate in
intraspecific ecological
interaction forming with
hundreds, thousands even millions
of . Water-permeated solid
structures these colonies, known
reefs, work as ecosystems for other
beings. The biggest coral
colony is Great Barrier Reef the
northeast coast Australia.There are
however coral species whose
live alone and not form
colonies.