A coral reef is made of thin layers of calcium carbonate. Coral polyps form a living mat over a calcium carbonate skeleton. Stony corals (or scleractinians) are the corals primarily responsible for laying the foundations of, and building up, reef structures.
<span>Equilibrium is your answer i believe.
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Answer: Wo meiyou xiansuo
Explanation:
The earth is about 6,000 years old.
