The center of the chamber houses a large crystal orb that can recall the most recent psionic echoes of any individual tuned to the various hundred other shards within the room. Should anyone want a specific shard, they need only ask the control panel at the bottom of the room and it will levitate said shard there.
Ihan chambers are essential for the use of exosuits as the process is taxing and the use of the crystals help restore enough brain activity to function relatively normally (Justice League - Unlimited: Kragger). Should the user of an Ihan crystal perish, their allies can use the memories to see just what lead up to that individual's death. This is often dangerous as another protoss must be possessed by the memories and can be overwhelmed by them if not mentally perpared (Stargate - Atlantis: The Long Goodbye).