Pyrovile

The Pyroviles were great beings of rock and fire, untill they crashed to Earth and eroded into particle-like beings. When breathed in, the Pyrovile would slowly take control of the body and turn the victim into living stone. They also gave pyschic powers to those who breathed them in.

The Pyrovile invasion planned to convert the power of Vesuvius eruption to change all humans into Pyrovile but The Doctor stopped this causing Mount Vesuvius to erupt. Apparently, their home planet Pyrovillia was taken from them.

The Pyroviles were also weak to water, and could be killed by it, as shown when the doctor kills a Pirovile with a water pistol. There are huge, humanoid, gladiator-like, stone beings that have been described by The Doctor as "foot soldiers" and even larger ones inside Vesuvius he describes as 'Fully Grown Pyrovile'. (DW: The Fires of Pompeii)