Ram's skull

The ram's skull was an object in Mr R's possession. It had a pentagram on it. Edgar Allan Poe thought it possible that Mr R had obtained the skull from Colonel Caine.

Mr R invited several people to a gathering involving the ram's skull. He hoped to use Abigail as a medium to contact another plane and achieve immortality. However, an evil entity possessed Abigail, and the skull began to grow flesh. It was destroyed by the First Doctor and Poe. (PROSE: The True and Indisputable Facts in the Matter of the Ram's Skull)