Iron meteorites contain Widmanstätten patterns—intricate geometric crystal structures that form when iron-nickel alloys cool at roughly 1-10°C per million years in the vacuum of space. These patterns are literally impossible to replicate on Earth without waiting geological timescales. The crystal lattice structures (kamacite and taenite phases) interlock at specific angles, creating natural fractals that reveal the thermal history of asteroid cores. Each pattern is unique, like a cosmic fingerprint of deep-space metallurgy frozen in time.