If this should be moved to another thread, somebody go ahead and move it.
Anyways whilst reading the new Graphic Novel Gathering of the Toa, in the Okoto Protector's Guide, I found some nifty info on the Gen 2 mask of time. This is mostly stuff we knew but it is now proven concretely. The text from the book is below.
Kept in a secret vault in the Temple of Time, the Mask of Time possesses powers that even the wisest elders don't completely understand. According to ancient legends, the Mask of Time is actually a fragment of a larger mask: it is the upper half that completes the true mask of time. The Protectors do not possess any records or illustrations regarding the lower half of the Mask of Time and are unaware of its location.
Pretty self-explanatory where/what the other half is. But what is the connection.
Also, some interesting info on the Temple of Time/
The Protectors also believe that the temple mystically connects Okoto with other places, including distant worlds, across time and space.
One possibility is that the Toa exist as legends outside of space-time and can be brought into existence by certain means (if I recall correctly, their creation story in Gen 1 is fairly vague). But that's just me.
Let the speculation commence!