Ood Brain
The Ood Brain was a huge living brain that under natural circumstances controlled the connection between individual Ood, facilitating their Hive mind. It was capable of telepathically reaching Ood over the distance of three galaxies. It is shown to be living as Klineman Halpern threw Ryder on to it and it swallowed him.
However some centuries before the 42nd century humans discovered the brain beneath the Northern Glacier on the Ood Sphere. By 4126 it was contained in warehouse 15 of Ood Operations, surrounded by a telepathic barrier so it couldn't communicate with the Ood. This, together with lobotomising the Ood, allowed them to enslave Oodkind. Dr. Ryder, an agent working for Friends of the Ood, managed to infiltrate Ood operations and after years of patience became into the position where he could covertly lower the intensity of the field, which first manifested itself as Red-eye and later resulted in a full-blown Ood rebellion. The Doctor eventually shut off the barrier freeing the Ood from slavery.
- It is unknown if the Ood brain served any function to Ood Operations, explaining why it was kept alive. Perhaps without it, the Ood would die..