Metal doesn't spontaneously rust on Earth for no reason. It does so to minimise energy. Rusting is exothermic, as you will observe in spectacular style with the Thermite reaction:

Al + FeO2 -> AlO2 + Fe

(I know this appears to be a de-rusting reaction, but Aluminium is more reactive than iron and has a greater affinity for Oxygen than does Iron. It rusts better, and faster, stealing the oxygen and producing reduced liquid iron at 3000 K.)

Water + Fe + O2 -> FeO2. If you grind the iron real fine and do this in an enriched oxygen atmosphere, it can get lively too. Did you ever see steel wool burn in an oxygen stream, or a thermal lance where a steel pipe stuffed with steel wool is flushed with oxygen, lit with an oxy-acetylene torch, and then combusts spectacularly - enough to melt through steel and concrete. The ideal safe-breakers tool.

Chemistry is fun, when done with high enough quantities and concentrations!

No life form could reduce oxidised iron unless it had available a far greedier metal than iron.