When you think of iron, you probably think of anvils and suits made by Tony Stark - iron is ore that comes from a mine.
Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.
Clark Johnson, a professor of geoscience at the University of Wisconsin-Madison, and former postdoctoral researcher Weiqiang Li examined samples from the banded iron formation in Western Australia. Banded iron is the iron-rich rock found in ore deposits worldwide, from the proposed iron mine in Northern Wisconsin to the enormous mines of Western Australia. These ancient deposits, up to 150 meters deep, were begging for explanation.