Feral Mechology

One type of planetary hazard, a feral mechology emerges when control is lost over robotic infrastructure which then goes on to form a more-or-less self-perpetuating mechanical ecology. This often happens as a consequence of war or some other disruptive event on a planet which uses automated infrastructure for terraforming, industry, or similar, especially if robots in said infrastructure have some capability for maintenance or self-replication. Once rendered feral, such drones can spread across a planet like any other life-form, competing to occupy habitats and even "evolving" from selection pressures. This often proves inconvient or dangerous to organic populations, who may attempt to disable or reassert control over renegade mechologies.