I think its just one of the 4 keys to the Temple of Time. The three spiritual stones are placed on the altar, but it takes the Ocarina of Time to "activate" them.

It was probably created by the sages along with the Temple of Time and the spiritual stones, and went to the royal family just as the stones went to 3 separate races.

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Caress the one, the never fading rain in your heart- the tears of snow-white sorrow.
Caress the one, the hiding amaranth in a land of the daybreak.