Synonym: Organic reef landscape
This is a general term for a landscape consisting of wave-resistant biogenic reef structures that have built up by in situ reef-building organisms. These islands are mainly located in deep tropical and sub-tropical seas. The reefs contain abundant fossils of reef-building creatures. In addition to corals, which are common reef-building organisms, there are many other organisms, such as algae, moss worms, calcareous sponges, stromatoporoids and archaeocyathids. The bioherms range in length from tens of metres to tens of kilometres and even hundreds of kilometres. The reefs can be circular, such as atolls, horseshoe-shaped, tower-shaped, and narrow and long like an embankment.