Zazz's moon

Zazz's moon was the moon of the planet Zazz.

Monektoni Shug crashed his spacecraft on the moon. A Servatron survived the crash and began building Self-Replicating Robots. They soon developed a city on the moon. A robot was taken back to Zazz and began increasing its number to the point at which it became a plague. The Doctor lured them into a rocket and sent them back to the moon. (DWM: The Gift)