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How changing levels of iron shaped the evolution of life on Earth – and why alien hunters should take note
![geophysics - Is the iron on Earth's crust a leftover of the Iron catastrophe, or it was brought back by volcanoes? - Earth Science Stack Exchange geophysics - Is the iron on Earth's crust a leftover of the Iron catastrophe, or it was brought back by volcanoes? - Earth Science Stack Exchange](https://i.stack.imgur.com/pSpKE.png)
geophysics - Is the iron on Earth's crust a leftover of the Iron catastrophe, or it was brought back by volcanoes? - Earth Science Stack Exchange
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