From Tardis Wiki, the free Doctor Who reference

The Archaeons were an advanced and ancient race of globular beings. They could mimic other species by replicating their form on their globular surface, allowing them to communicate. They fancied themselves the propagators of life, who brought "order to primal worlds" by seeding planets with life in the early stages of their development. Their propagation mission to Earth was led by the First Propagator.

When the First Doctor, Susan and Quadrigger Stoyn encountered them around 450 million BC, they were situated on the moon and were seeding the Earth with life, using a large cannon that shot red lightning. When the Archaeons tried to disassemble the TARDIS, they took the temporal stasis capacitor out, unintentionally creating a stasis field which froze them all in time until human explorers from the Giant Leap Base freed them millions of years later.

Blaming the Doctor for ruining their experiment, they planned to eradicate the disorderly humans on the Earth and Moon. However, the humans retaliated with missiles, destroying the Archaeons. (AUDIO: The Beginning)