The Body Electric
Asmoray was a quartz planet wrapped around a copper core. It acted as a giant natural electrical transmitter.
The Twelfth Doctor took Clara Oswald to Asmoray’s Quartz Wastes, calling it a “stunning natural phenomena”. He believed the planet to be devoid of life and was surprised to a building on the planet used for harvesting electricity. The Doctor and Clara were taken to Luther, the man in charge of the harvesting, and accused of trespassing. Upon investigation, they discovered alien entities lived within the planet’s electricity and were killing the harvesters in defence of being repeatedly routed through the harvester. The Doctor used his sonic to shut the machine down and free the Asmoray natives. (The Body Electric)