Some bacteria "breathe" metal instead of oxygen

Humans and most animals breathe by using oxygen as the final step in extracting energy from food — which is exactly why we die within minutes without it.

Metal-reducing bacteria, living in low-oxygen sediments and soils, can use substances like iron oxide or manganese oxide as their "electron acceptor" instead of oxygen — compounds most organisms would simply treat as inorganic rock.

In practice, this means these microorganisms literally "breathe metal" — chemically, the process plays the exact same role as oxygen breathing, just with a completely different reaction partner at the end of the chain.

Some of these bacteria are now being studied for practical applications — from cleaning up metal-contaminated soil and water, to building "living batteries" that generate electricity as a byproduct of their metabolism.