26/05/2026
3.46 billion years ago Earth’s oceans had no oxygen so iron dissolved in water like salt, then cyanobacteria started making O2 and the oceans rusted in real time; the result is banded iron: 2km-thick layers of red iron oxide and white silica stripes that record Earth’s first mass poisoning event — the rusting of the seas — and those formations are now 60% of the world’s iron ore, so every skyscraper is built from the scar tissue of Earth’s first breath.