English:
Stromatolite
Stromatolites are formed over the years by mats (1-10 mm in thickness) of microorganisms (cynobacteria among others) found in shallow, mainly marine waters. The microorganisms precipitate mineral particles, which makes the mat to thicken, but only the upper part survives. Most stromatolites display characteristically layered structures. Only the layers are visible to the naked eye.
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Stage :
Paleoarchean
from -3 600 à -3 200 Ma (million years ago).
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Locality: Strelley Pool Chert (SPC) (Pilbara Craton) - Western Australia.