Coral reef islands and atolls. The reef face is the zone above the reef floor or the reef drop-off. This zone is often the reef's most diverse area. Coral and calcareous algae provide complex habitats and areas that offer protection, such as cracks and crevices. Invertebrates and epiphytic algae provide much of the food for other organisms. A common feature on this forereef zone is spur and groove formations that serve to transport sediment downslope. The reef flat is the sandy-bottomed flat, which can be behind the main reef, containing chunks of coral. This zone may border a lagoon and serve as
Tema Reef 1765. Captain William Williams of the missionary ship "John Williams" sighted the reef on May 15, 1864. It was again examined by in 1880. Tema Reef Tema Reef, also called Tima Reef, is a submerged coral reef in the northern Cook Islands, southeast of Pukapuka. No coral or rock shows above water, but the sea breaks heavily over the reef. The reef measures about , covering a shallow but submerged area of . Legend has it that Tima, an Aitutakian warrior sailed to Nassau, but was chased away by Ngalewu, a chief from Pukapuka. On his return to Aitutaki he