The Twist was originally a colony ship from Earth, carrying human colonists in a stasis farm, along with other animal and plant species housed, in two biodomes. The Twist itself was extruded, or "grown", from a matter seed on the ship.
At some point during the ship's journey, a complete system failure killed all the colonists on board. Eventually the Foxkin evolved from the foxes on the ship. The Foxkin discovered the human colonists and worked out what had happened to them. They then cloned the human remains and grew a new set of colonists, secretly guiding them.
The Twelfth Doctor arrived on the Twist, and with the help of Hattie Munroe, discovered the true history of the Twist and helped the Foxkin reveal themselves and be accepted into the human society. (COMIC: The Twist)