Pyrovile

The Pyroviles were a species of large humanoid beings made of lava contained in rock. There are huge gladiator-like stone beings. There are two types of Pyrovile one smaller one described as "Foot solders" and larger ones inside Vesuvius he describes as 'Fully Grown Pyrovile'. Apparently, their home planet Pyrovillia was taken from them.

A group of Pyroviles crashed on Earth and over millions of years eroded into dust particles. However, they were not lost, as they awoke by an earthquake in 62 AD and when breathed in by Humans these particles would slowly transform the humans into Pyroviles themselves. The transformation would first result in petrification of limbs, and psychic powers. In a more advanced stadium, a sort of hybrid form was achieved, a human-like 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, which is lethal in adult Pyroviles, as evident when Quintus threw a bucket of water over one, killing it.

By 79 AD adult Pyrovilles had created a base beneath mount Vesuvius and were planning to convert the power of the volcano eruption to change all humans into Pyrovile but The Doctor stopped this, causing Mount Vesuvius to erupt. (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. possibly 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 reasembe and could proceed with their mission.