The Necrons' underground tombs are generally quite large and cavernous, containing repair facilities that are manned by Canoptek Scarab robots that repair the Necrons that were critically damaged in recent battles. They have stasis units, in which the dormant Necrons hibernate. They also usually have a large room in which either the Necron Lord or Necron Overlord that commands the Tomb World (occasionally called a Platinum Lord or a Tomb Lord) sleep in a massive and ornate black stone sarcophagus.