From Longman Dictionary of Contemporary Englishcoral reefˌcoral ˈreef noun [countable] HEOa line of hard rocks formed by coral, found in warm sea water that is not very deep
Examples from the Corpus
coral reef• If the system started to drift away from the requirements of a coral reef, Gomez would flush the trays.• Marine scientists were pretty sure a coral reef, like any complex ecosystem, must be assembled in the correct order.• Where does the synthetic coral reef end and the chanting wave machine begin?• Five years after Gomez launched the coral reef, it is only now configuring itself into self-sustenance. 