What Substance Builds Coral Reefs

Question

What substance builds coral reefs?
A) the limestone skeletons of dead coral
B) rock formations on the ocean floor
C) inactive volcanoes
D) the skeletal remains of fish

Accepted Answer

Coral reefs are built by the accumulation of the limestone skeletons of dead coral polyps. As live polyps produce new layers of calcium carbonate, the old, dead ones remain as the foundation of the reef. Over time, this accumulation builds up into the complex and diverse structure of a coral reef.