Acropora corals build their skeletons by depositing calcium carbonate (aragonite) beneath the living tissue layer through a process called calcification. Specialized cells within each coral polyp extract calcium and carbonate ions from seawater and combine them to form a rigid limestone skeleton.
Growth occurs primarily at the axial corallite located at the branch tip, where new skeletal material is rapidly produced, while radial corallites along the branch sides continue to thicken and strengthen the colony. Symbiotic zooxanthellae algae living within the coral tissue provide energy through photosynthesis,
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