Metalkind

The Metalkind were a race of boron-based lifeforms.

History
The Metalkind went to war with a Fleshkind race that lived on the twin planet of their homeworld after they mined ore (in actuality, the Metalkind's children) from the Metalkind planet. By Earth's 21st century, the war had raged on for hundreds of years.

When the Fleshkind lost a living weapon that could destroy the Metalkind, a Metalkind came to Earth in search of it. The Metalkind was damaged when the weapon unleashed her energies against it. The creator of the weapon, Myers, used the Metalkind to summon its race to Earth, intending for her creation to destroy them all. Myers' plan was foiled by Sarah Jane Smith and her allies. The Metalkind then freed itself and took Myers with it back to its homeworld. (TV: Sky)