Coral reefs are formed by ________
A
Volcanic rocks
B
Marine sediments
C
Chlorine material precipitated from sea water
D
Tiny colonial marine animals which construct limestone skeleton material
Correct Answer: Tiny colonial marine animals which construct limestone skeleton material
Coral reefs are formed by tiny colonial marine animals which construct limestone skeleton material. Massive reef structures are formed when each individual stony coral organism or polyp secretes a skeleton of calcium carbonate.