Coral reef a protective area, or it may lie between the reef and the shore, and in this case is a flat, rocky area. Fish tend to prefer it when it is present. The reef lagoon is an entirely enclosed region, which creates an area less affected by wave action and often contains small reef patches. However, the "topography of coral reefs is constantly changing. Each reef is made up of irregular patches of algae, sessile invertebrates, and bare rock and sand. The size, shape and relative abundance of these patches changes from year to year in response to the various factors
Open brain coral reef communities, and are more often found on sandy reef slopes, around continental islands, and lagoons. Open brain corals can often be found near other free-living corals. Large colonies of open brain corals are uncommon, and are typically only observed in marine protected areas. The IUCN lists open brain corals as "near threatened" due to habitat loss and over-harvesting for the aquarium trade. The biggest exporter of open brain coral is Indonesia. In 2005, Indonesia exported over 60,000 open brain corals for use in the aquarium trade. Other threats to open brain corals include disease, acidification, and severe storms. Open