In 2040, an ancient life form which fed on conflict had binged to the point of collapse. Needing to rest, it took up residence in a Buildworth domicile block as it was free from human interaction. It relived the conflicts it had fed upon, which manifested as "ghosts" in Manda's rooms.
The Seventh Doctor discovered where it was resting, and made plans to have it destroyed before it could recover and begin feeding again. He first collected its spores (which resembled stick-like tendrils) and mailed them to each of the residents. He then spoke to the residents individually, telling them about the creature, the threat it posed and what they needed to do about it, which was to start talking with each other, sharing their thoughts and feelings, something which it could not tolerate. (PROSE: Separation)