The Testimony Foundation was an organisation created on New Earth in the year 5,000,000,012 by professor Helen Clay of the University of New Earth. Its purpose was to allow the dead of the past to give their testimony of their lives in order for future generations to learn from the past. In exchange, the deceased would be granted a new form of life as glass avatars in order to interact with humans. (TV: Twice Upon a Time)
The Testimony Foundation employed a starship capable of time travel. It contained a claw mechanism which it could use to lift objects such as the Doctor's TARDIS and was capable of emitting a signal that prevented the captured ship from taking off. The ship's interior housed the 'Chamber of the Dead', which had rows of archways from which glass avatars could be summoned and projected. In the centre was a staircase which led to a computer and a chair where the pilot's avatar was situated.
The Foundation employed memory extraction techniques in order to copy a person’s memories and then transplant them into a glass avatar. These avatars were in every respect the person they appeared as, but were also part of Testimony. A single avatar had a variety of capabilities: one could freeze time around it to extrapolate people for questioning, teleport across different time periods and locations and project a perception filter around itself and others. An avatar could also shift between its default form, that of an androgynous transparent humanoid, and the form of the person it manifested as. (TV: Twice Upon a Time)