Corals are animals whose bodies consist of a single layer of cells

Answer and Explanation:

Corals are a type of invertebrate within the phylum Cnidaria. They live in colonies of many identical individual polyps. A set of tentacles surround a central mouth opening. They also have a simple, radially-symmetrical body containing a single opening that serves as both the mouth and anus. The body is made up of two layers of cells, separated by a jelly-like layer with no internal organ. The two layers of cells make a single cell surrounding the body.