|Function||Releasing the Bahrag|
The Nuva Cube was the lock on the cage that the Bahrag were trapped in. It could only be opened by the six Nuva Symbols.
The only way that the Nuva Cube could be unlocked was by placing all six of the Nuva Symbols, which respectively served as six different keys, into the correct slots. The Nuva Symbols were located in the Suvas of each Toa's village, where they would be safe. However, as the Toa Nuva had a connection to the Nuva Cube, when the Bohrok-Kal stole thier Nuva Cubes it caused them to lose their Elemental Powers and caused their Kanohi Nuva to change into a darker color.
The Bohrok-Kal then procceded to try and unlock the Nuva Cube until the Toa Nuva managed to use the Kanohi Vahi to slow them down. They then touched their Nuva Symbols, giving the Bohrok-Kal their powers. However, this was too much for them to control and their powers backfired on them, leaving the Toa Nuva to scoop up the Nuva Symbols and restore their Elemental Powers.