Editing Coral reef (section)

===Atoll===
{{main|Atoll}}
[[File:Coral atoll formation animation.gif|thumb|Formation of an atoll according to [[Charles Darwin]]]]
Atolls or [[atoll reef]]s are a more or less circular or continuous barrier reef that extends all the way around a lagoon without a central island.<ref>Hopley, David. ''Encyclopedia of Modern Coral Reefs: Structure, Form and Process.'' Dordrecht: Springer, 2011, p. 51.</ref> They are usually formed from fringing reefs around volcanic islands.<ref name=CRA/> Over time, the island [[erosion|erodes]] away and sinks below sea level.<ref name=CRA/>  Atolls may also be formed by the sinking of the seabed or rising of the sea level. A ring of reefs results, which enclose a lagoon.  Atolls are numerous in the South Pacific, where they usually occur in mid-ocean, for example, in the [[Caroline Islands]], the [[Cook Islands]], [[French Polynesia]], the [[Marshall Islands]] and [[Micronesia]].<ref name=CRI/>

Atolls are found in the Indian Ocean, for example, in the [[Maldives]], the [[Chagos Islands]], the [[Seychelles]] and around [[Cocos Island]].<ref name=CRI/> The entire Maldives consist of 26 atolls.<ref>[http://www.mymaldives.com/maldives/atolls/ ''Maldives Atolls''] at www.mymaldives.com. Retrieved 2 Feb 2018.</ref>