Editing Cloudinidae (section)

==Morphology==
[[File:Cloudina internal 01.png|thumb|left | 100px | Cutaway diagram of ''Cloudina'' showing "living space" within the shell.]]
''Cloudina'' varies in size from a diameter of 0.3 to 6.5&nbsp;mm, and 8 to 150&nbsp;mm in length.<ref name=Description>{{cite journal
| doi=10.2475/ajs.272.8.752
| author=Germs, G.J.B. | title=New shelly fossils from Nama Group, South West Africa
| journal=American Journal of Science |date=October 1972 | volume=272 | pages=752–761
| issue=8
| bibcode=1972AmJS..272..752G}}</ref>  Fossils consist of a series of stacked vase-like [[calcite]] tubes, whose original mineral composition is unknown,<ref name="Porter2007">{{cite journal
| journal=Science | date= 1 June 2007 |volume= 316 |issue=5829 |doi= 10.1126/science.1137284
| title= Seawater Chemistry and Early Carbonate Biomineralization |author=Porter, S.M.
| pages = 1302 | pmid= 17540895 | bibcode=2007Sci...316.1302P
| s2cid= 27418253 }}</ref> but inferred to be high-magnesium calcite.<ref>1. Zhuravlev, A.Y., Wood, R.A., and Penny, A.M. (2015). Ediacaran skeletal metazoan interpreted as a lophophorate. Proc. R. Soc. B 282, 20151860. Available at: http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2015.1860.</ref> Each cone traps a significant pore space beneath it, and stacks eccentrically in the one below. This results in a ridged external appearance.  The overall tube is curved or sinuous, and occasionally branches. The tube walls are 8 to 50 micrometers thick, usually lying in the range 10 to 25 μm.<ref name="Grant1990" /> Although it used to be thought that the tubes had test-tube like bases,<ref name="Description" /> detailed three-dimensional reconstruction has shown that the tubes had an open base.<ref name="Miller" /> There is evidence that the tube was flexible.<ref name="Brain2001" />