Self-replicating robot

Self-replicating robots were scavenging robots who could build more of their numbers.

Abilities
The robots were capable of self replicating from available materials. They had individual intelligence allowing them to act for their own benefit. They were able to function underwater. The Sixth Doctor described them as a plague. (DWM: The Gift)

Origins
Monektoni Shug's spacecraft crashed on Zazz's moon. A Servatron was onboard and it survived the crash. The robot began repairing the ship and creating more robots. After twenty generations on this moon they had built their own city.

They were forced to periodically scramble when a warning alarm rang for a meteorite shower; they hid underground. Later a meteor storm came and one large meteor hit and destroyed the city, killing the robots. Professor Strut found a robot in a rock sample he took from the moon to Zazz.

On Zazz
Professor Strut gave a package to the Doctor, telling him it was a present for his brother, the Lorduke of Zazz. The package contained a single self-replicating robot. The Doctor presented it to the Lorduke at a party. The robot emerged and began to create more or its kind until they swarmed the area. They took any metal they found for the creation of more robots. One robot even stole the Doctor's watch chain.

The Doctor used a sound similar to the meteor recall alarm to lure the robots on Zazz to Strut's rocket. The rocket took them to the moon. (DWM: The Gift)