Pyrovile

The Pyroviles were a species of rock-based humanoids from the planet Pyrovillia.

Biology
Pyroviles were humanoids with a rock-based form with a magma-based interior, and so could be killed by sufficient quantities of water. They were tall beings, reaching up to about 10 metres in hight and resembling oversized Roman soldiers.

Pyroviles came in two varieties - a shorter, easily-destroyed "Foot Soldier" and more advanced, fully grown Pyroviles which could reach over twice the height.


 * However, the Pyroviles may only have be of this form as they took over Human bodies.

History
At some point in their history, the Pyroviles developed advanced technology from rock, and could travel into space. When their homeworld was lost, a group of Pyroviles escaped in an escape pod, eventually crashing on Earth. The Pyroviles were obliterated in the explosion and eroded into dust particles in the core of Mount Vesuvius.

However, they were not lost, as they awoken by an earthquake in 62 AD and when breathed in by Human prophets these particles would slowly transform the humans into Pyroviles themselves. The transformation would first result in petrification of limbs, and psychic powers granted by the Pyrovile using the latent power of the Human brain. In a more advanced stadium, a sort of hybrid form was achieved, a humanoid figure made of stone. By this point, the being would act as if it was a Pyrovile and also started to exhibit negative reactions to exposure to water.



By 79 AD full-grown Pyrovilles had created a base beneath Vesuvius and were planning to convert the power of the volcano eruption to change all Humans into Pyroviles. However, the Doctor stopped this, and in the process caused Mount Vesuvius to erupt and destroy the Pyroviles and the nearby town of Pompeii. (DW: The Fires of Pompeii)


 * It is unknown if the Pyrovile plan was to turn the Earth in a Pyrovile planet from the start, and if so, why they waited so long. Premumably their initial pulveration into dust might have been accidental, and it wasn't until humans started to breathe in the dust that the creatures started to reassemble and could proceed with their mission.