Editing Microfossil (section)

===Calcareous===
The term ''calcareous'' can be applied to a fossil, sediment, or sedimentary rock which is formed from, or contains a high proportion of, [[calcium carbonate]] in the form of [[calcite]] or [[aragonite]]. Calcareous sediments ([[limestone]]) are usually deposited in shallow water near land, since the carbonate is precipitated by marine organisms that need land-derived nutrients. Generally speaking, the farther from land sediments fall, the less calcareous they are. Some areas can have interbedded calcareous sediments due to storms, or changes in ocean currents. [[Calcareous ooze]] is a form of calcium carbonate derived from planktonic organisms that accumulates on the [[sea floor]]. This can only occur if the ocean is shallower than the [[carbonate compensation depth]]. Below this depth, calcium carbonate begins to dissolve in the ocean, and only non-calcareous sediments are stable, such as [[siliceous ooze]] or [[pelagic red clay]].

{|class="wikitable"
! colspan=8 |{{center|[[Calcareous]] ooze}}
|-
! mineral<br />forms
! protist<br />involved
!
! name of skeleton
! width=100px | typical size
! colspan=2 |
|-
|  width=90px rowspan=3 align=center | [[Calcium carbonate|CaCO<sub>3</sub>]]<br />[[calcite]]<br />[[aragonite]]<br />[[limestone]]<br />[[marble]]<br />[[chalk]]
| [[foraminiferan]]
| style="background:#000000;"| [[File:Foram-globigerina hg.jpg|90px]]
| [[Foraminifera test|test]] or shell
| many under 1&nbsp;mm
| [[File:Globigerina.png|100px]]
| [[Calcified]] [[Foraminifera test|test]] of a planktic foraminiferan. There are about 10,000 living species of foraminiferans<ref name="adl2007">{{cite journal | last1 = Ald | first1 = S.M. | display-authors = etal | year = 2007 | title = Diversity, Nomenclature, and Taxonomy of Protists | journal = Syst. Biol. | volume = 56 | issue = 4 | pages = 684–689 | doi = 10.1080/10635150701494127 | pmid = 17661235 | doi-access = free }}</ref>
|-
| [[coccolithophore]]
| style="background:#000000;"| [[File:Coccolithus pelagicus 2.jpg|90px]]
| [[coccolith]]s
| under 0.1&nbsp;mm{{hsp}}<ref name=Moheimani2012>{{citation |journal=[[Algal Research]] |volume=1 |issue=2 |year=2012 |pages=120–133 |title=Bioremediation and other potential applications of coccolithophorid algae: A review. . Bioremediation and other potential applications of coccolithophorid algae: A review |first1=N.R. |last1=Moheimani |first2=J.P. |last2=Webb |first3= M.A. |last3=Borowitzka |doi=10.1016/j.algal.2012.06.002}}</ref>
| [[File:CSIRO ScienceImage 7202 SEM Coccolithophorid.jpg|100px]] 
| Coccolithophores are the largest global source of biogenic calcium carbonate, and significantly contribute to the global [[carbon cycle]].<ref>{{cite journal | last1 = Taylor | first1 = A.R. | last2 = Chrachri | first2 = A. | last3 = Wheeler | first3 = G. | last4 = Goddard | first4 = H. | last5 = Brownlee | first5 = C. | year = 2011 | title = A voltage-gated H+ channel underlying pH homeostasis in calcifying coccolithophores | journal = PLOS Biology | volume = 9 | issue = 6| page = e1001085 | doi = 10.1371/journal.pbio.1001085 | pmid = 21713028 | pmc = 3119654 | doi-access = free }}</ref> They are the main constituent of chalk deposits such as the [[white cliffs of Dover]].
|-
|}

<gallery mode=packed heights=160px style=float:left;>
File:Nanoplankton-fossil-sediment hg.jpg| {{center| Calcareous microfossils from marine sediment consisting mainly of star-shaped [[discoaster]] with a sprinkling of coccoliths}}
File:PSM V44 D483 Globigerina ooze.jpg|Illustration of a ''[[Globigerina]]'' ooze
File:FMIB 47660 Shells from Globigerina Ooze.jpeg|Shells ([[Test (biology)|tests]]), usually made of calcium carbonate, from a [[foraminifera]]l ooze on the deep ocean floor
</gallery>

[[File:Mesozoic benthic foraminifera.png|thumb| {{center|[[Mesozoic]] benthic foraminifera{{hsp}}<ref>{{cite journal |doi = 10.5194/jm-37-395-2018|title = New species of Mesozoic benthic foraminifera from the former British Petroleum micropalaeontology collection|year = 2018|last1 = Fox|first1 = Lyndsey R.|last2 = Stukins|first2 = Stephen|last3 = Hill|first3 = Tom|last4 = Bailey|first4 = Haydon W.|journal = Journal of Micropalaeontology|volume = 37|issue = 1|pages = 395–401|bibcode = 2018JMicP..37..395F|hdl = 10141/622407|hdl-access = free | doi-access=free }}</ref>}}]]

[[File:Oscillatoriopsis longa fossil.jpg|thumb|upright=0.8|center| {{center|[[Cyanobacteria]]l remains of an annulated tubular microfossil ''Oscillatoriopsis longa''{{hsp}}<ref>{{cite journal |doi = 10.1111/pala.12374|title = First record of Cyanobacteria in Cambrian Orsten deposits of Sweden|year = 2018|last1 = Castellani|first1 = Christopher|last2 = Maas|first2 = Andreas|last3 = Eriksson|first3 = Mats E.|last4 = Haug|first4 = Joachim T.|last5 = Haug|first5 = Carolin|last6 = Waloszek|first6 = Dieter|journal = Palaeontology|volume = 61|issue = 6|pages = 855–880| bibcode=2018Palgy..61..855C |doi-access = free}}</ref><br /><small>Scale bar: 100 μm</small>}}]]

{{clear}}