The sundial was reduced in size by the Order of Mata Nui using a shrink disk and was later given to Takanuva. By shining his light on the sundial, Takanuva could create a shadow that would point in the direction of the Karda Nui Codrex.
Lewa retrieved the sundial from Mata Nui. The Order of Mata Nui shrank the sundial and gave it to Takanuva. When Takanuva shone light upon it, the shadow it produced pointed toward the spot from which Mata Nui could be awakened.