Ronan (species)

The Ronans were a race of highly intelligent, large, ape-like creatures from the planet Ronos. Ronos was a dry planet without seas and a spiral orbit that took it ever further away from its sun and as the planet grew colder the Ronans began to drill through the planets crust to release the energy from the core. This attempt to save the planet led to its ultimate destruction and both planet and the Ronans died out.

A small craft of Ronans managed to escape before their planets destruction and, encountering the Earth, sought to repeat the action by drilling down into the planets core beneath the Dead Sea using the local people as slaves. The Fourth Doctor’s intervention saw their network of tunnels flooded by salt water and the Ronans driven underground trapped by the salt water that they were allergic too. (DWM: The Heat-Seekers)