deo , 5 months ago

Not the first. The cyanobacteria that first figured out photosynthesis put so much oxygen into the atmosphere so fast that it cause mass extinction of much of the anaerobic life (and most things were anaerobic life back then). They also caused a literal rust belt (since many metals up to that point were now able to be oxidized en masse), and that rust layer can be seen in really old rocks (“banded iron formation”).

Great Oxidation Event