Montastraea

Montastraea is a genus of colonial stony coral found in the Caribbean seas. It is the only genus in the monotypic family Montastraeidae and contains a single species, Montastraea cavernosa, known as great star coral. It forms into massive boulders and sometimes develops into plates. Its polyps are the size of a human thumb and fully extend at night.

==Description== thumb|left|Close-up with polyps extended Great star coral colonies form massive boulders and domes over 5 feet (1.5 m) in diameter in waters of shallow and moderate depths. In deeper waters, this coral has been observed growing as a plate formation. It is found throughout most reef environments, and is the predominant coral at depths of 40–100 feet (12.2–30.5 m).