A bank of coral is a geological formation consisting of coral material and other sediments. This natural structure is also known as a coral reef or coral bank. There are several other synonyms for the term "bank of coral," including coral shoal, coral cay, and coral atoll. A coral shoal is a submerged bank of coral that is close to the surface of the water. A coral cay, on the other hand, is an accumulation of sand and coral that is formed above water. Lastly, a coral atoll is a ring-shaped coral reef that surrounds a lagoon. These varied synonyms help describe the diverse shapes and types of coral formations found in oceans around the world.