The Spiegel Stone was created by The 1st Shadow when experimenting with the fabric of universes shortly after BZ-Nui was first created. He found an empty universe and condensed it into a crystal, planning to use it as a failsafe for the Kanohi Force tower. He was able to create a copy of the tower, which he stored inside of the Spiegel Stone. He kept it locked away until many decades later.
On the night before the creation of GhidoraT1S, Shadow entrusted the stone to Irrie, telling him to keep it in safekeeping until he returned. Irrie took it with him after he escaped from imprisonment and fled to the wild. He stopped by his old shack in the mountains and put it there before going to the Bleak Lands.
Much later, the stone was recovered by Irrie when he, Finbarr, and Rustam entered into the shack after the destruction of the transport. Shadow and Arzaki arrived the next day, and they took it to a flat space in the mountains, where they activated it again, summoning the Kanohi Force tower once again. After the stone exploded, Shadow used his Kiril to rebuild it, enabling it to become usable again.