The term 'Reef Material' can be summarized by the crossword solution of 'CORAL, ' which is a type of marine organism that forms large, underwater structures. CORAL is composed of calcium carbonate and is made up of many individual organisms called polyps. These polyps form colonies and secrete a hard, protective skeleton that helps to create the structure of the reef. CORAL reefs are some of the most diverse ecosystems in the world and provide habitats for a wide variety of marine life.