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Collenia undosa Walcott 1916

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Here is a nice Stromatolite plate from the deep Precambrian of the USA, Es is a polished slap with the speices Collenia undosa from the about 2.2 Billion years old Biwabik-Iron-Formation of Minnesota. The Site of the Mary Ellen Mine is a classical Banded Iron Formation. Locality. It is knon and valoured for its nice and colourfully preservation. These decorative Stromatolite fossils are sometimes even used for jewellery. The Cyanobacteria that where incorporated in the bounding of this Stromatolite have likely produced significant amounts of oxygen. This free oxygen bond the Fe² that was solved in the ancient oceans. This process produced the Banded Iron Formations (also known as BIF’s ) world wide at that time in earth history. After all the iron was used up by that process the oxygen concentrations in the Atmosphere and ocean could rise. What lead to the great oxygen crisis (sometimes also known as the first big extinction). How ever the higher levels of oxygen allowed the life eventually to become more complex.

	Location:	Mary Ellen Mine, Mesabi Range, St. Louis County, Minnesota, USA
	Size :	about 85 x 44 mm
	Age:	Precambrian, Lower Proterozoic, Rhyacian, Biwabik Formation (about 2.2 Ga / 2200 Ma)

Product no.: 10468