Coral reefs are built by a small organism called a polyp. the polyp creates the structure of the coral reef by building a out of calcium carbonate

cup

pocket

shelf

plate

The correct answer that would best complete the given statement above would be the first option. Coral reefs are built by a small organism called a polyp. The polyp creates the structure of the coral reef by building a CUP out of a calcium carbonate. The skeletons of these tiny corals secreted by the lower portion of the polyp. Hope this answer helps.