A Memory Stone was a relic used by the Anibusians.
The Memory Stone was part of the mourning ritual. One stone would be placed with the corpse, and the other would be worn by the mourner. The stones allowed the mourner to gradually come to terms with the loved one's death.
Memory Stones had an adverse affect on humans, especially if they had any telepathic ability. Vivian brought one back from Anibus, and it caused both her and Tony Deek to see her dead fiancé Steven Mead. (PROSE: Christmas Spirit)