Answers

2014-08-09T13:05:42+05:30
The formal definition of a reef is a ridge of rock or shingle or sand at or just below the surface of the water. 
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2014-08-09T13:06:51+05:30
actually its coral reef and coral reefs are diverse underwater ecosystems held together by calcium and reef-dwelling corals have a symbiotic relationship with algae.
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