The Cradle

 was a musical instrument and memory device similar to a harp that was used by the Claw Shansheeth. While it was played, it induced memories, collected them, and gauged their strength. The effect could be strengthened to induce sleep. It could create holographic views of collected memories or show visuals those affected. The Cradle was used in conjunction with the memory weave. (TV: Death of the Doctor)