Editing Reef (section)

=== Geologic ===
<!-- target for redirect [[Rocky reef]] -->
Rocky reefs are underwater outcrops of rock projecting above the adjacent unconsolidated surface with varying relief. They can be found in depth ranges from [[intertidal]] to deep water and provide a substrate for a large range of sessile benthic organisms, and shelter for a large range of mobile organisms.<ref name="NOAA fisheries" /> They are often located in sub-tropical, temperate, and sub-polar latitudes.
{{expand section|relative abundance of rocky vs biotic reef and global distribution, ecological importance|date=February 2021}}

==== Structures ====
[[File:Fossil Reef Windley Key 1.jpg|thumb|Fossil [[brain coral]] (''Diploria'') at the [[Windley Key Fossil Reef Geological State Park]].  [[Quarter (United States coin)|US Quarter]] near top for scale.]]

Ancient reefs buried within [[stratigraphy|stratigraphic]] sections are of considerable interest to [[geologist]]s because they provide paleo-environmental information about the location in [[history of Earth|Earth's history]]. In addition, reef structures within a sequence of [[sedimentary rock]]s provide a discontinuity which may serve as a trap or conduit for [[fossil fuel]]s or mineralizing fluids to form [[petroleum]] or [[ore deposit]]s.<ref>{{Cite journal |last1=Gorokhovich |first1=Yuri |last2=Learning |first2=Lumen |title=Coastal Geology: Shorelines |url=https://pressbooks.cuny.edu/gorokhovich/chapter/coastal-geology-shorelines/ |language=en}}</ref>

Corals, including some major extinct groups [[Rugosa]] and [[Tabulata]], have been important reef builders through much of the [[Phanerozoic]] since the [[Ordovician]] Period. However, other organism groups, such as calcifying algae, especially members of the red algae ([[Rhodophyta]]), and molluscs (especially the [[rudists|rudist]] bivalves during the [[Cretaceous]] Period) have created massive structures at various times.

During the [[Cambrian]] Period, the conical or tubular skeletons of [[Archaeocyatha]], an extinct group of uncertain affinities (possibly sponges), built reefs.<ref>{{Cite web |title=Archaeocyathans |url=https://ucmp.berkeley.edu/porifera/archaeo.html#:~:text=The%20first%20archaeocyaths%20appear%20roughly,creation%20of%20the%20first%20reefs. |access-date=2024-04-20 |website=ucmp.berkeley.edu}}</ref> Other groups, such as the Bryozoa, have been important interstitial organisms, living between the framework builders. The corals which build reefs today, the [[Scleractinia]], arose after the [[Permian–Triassic extinction event]] that wiped out the earlier rugose corals (as well as many other groups). They became increasingly important reef builders throughout the [[Mesozoic]] Era.<ref>{{Cite journal |last1=Pruss |first1=Sara B. |last2=Bottjer |first2=David J. |date=2005-09-01 |title=The reorganization of reef communities following the end-Permian mass extinction |url=https://www.sciencedirect.com/science/article/pii/S163106830500045X |journal=Comptes Rendus Palevol |volume=4 |issue=6 |pages=553–568 |doi=10.1016/j.crpv.2005.04.003 |bibcode=2005CRPal...4..553P |issn=1631-0683|url-access=subscription }}</ref> They may have arisen from a rugose coral ancestor.

Rugose corals built their skeletons of [[calcite]] and have a different symmetry from that of the scleractinian corals, whose skeletons are [[aragonite]].<ref>{{Cite web |date=2021-06-30 |title=Rugose Coral |url=https://www.colorado.edu/cumuseum/2021/06/30/rugose-coral |access-date=2024-04-20 |website=Museum of Natural History |language=en}}</ref> However, there are some unusual examples of well-preserved aragonitic rugose corals in the [[Lopingian|Late Permian]]. In addition, calcite has been reported in the initial post-larval calcification in a few scleractinian corals. Nevertheless, scleractinian corals (which arose in the middle Triassic) may have arisen from a non-calcifying ancestor independent of the rugosan corals (which disappeared in the late Permian).<ref name=":0" />