Kandasi was a gigantic spacecraft (later, space station) made out of living metal. The Panjistri used it to escape the destruction of their homeworld.
It later came into Kirith's orbit, and was believed by the Kirithons to be their world's second moon. Its high gravity disrupted weather patterns on Kirith. The Panjistri set up a matter transporter on Kandasi Island for travel to and from Kirith.
Kirithons were told that they would be taken to Kandasi to join the "Brotherhood of Kandasi", but in fact were being absorbed into the God Machine. The Seventh Doctor and Ace, accompanied by Arun and Raphael, came to Kandasi to stop the Panjistri, where they learned from Reptu of the plan to create the God Machine. When the Timewyrm completely took over the Grand Matriarch, the station's systems began began failing, having been maintained by their leader's telepathic control. After everyone was evacuated, the God Machine destroyed Kandasi. (PROSE: Timewyrm: Apocalypse)