The Sands of Time was a Shen Gong Wu. When this Shen Gong Wu was activated, it allowed the user to travel to either the past or future, depending on which one the user is thinking of. It could always change time, in good ways and bad.
This Shen Gong Wu resembled that of an hour glass, with detailed design on the top and bottom and red sand inside. It was gold and black in color, with clear glass.
When this Shen Gong Wu was activated, it allowed the user to not only travel through time but to alter time as well. According to Master Fung, time could always be changed with this Shen Gong Wu. It had been used a couple times in the Xiaolin Showdown Series but it is now hidden somewhere in the future by the future version of Omi.
This Wu was used by Jack Spicer to bring some of history's worst villains to the present. It was obtained by the Xiaolin, and Omi's future self took it with him to hide it, so that it would be safe from the wrong hands. It was later stolen from the alternate-future emperor of the world, Jack Spicer, by Omi to escape to the far past. Unfortunately, after travelling back to the present, now much different from when he left, it was destroyed by Hannibal Bean with the Kuzusu Atom. However, as a paradox was caused, the Sands of Time still remained where Omi's future self had originally hidden it.
Old Omi (208: "The Sands of Time" - 312: "Time After Time: Part I")
Omi (312: "Time After Time: Part I" - 313: "Time After Time II")
Xiaolin (313: "Time After Time: Part II")
Did you know?
It's technical first appearance was in "Days Past", used by Grand Master Dashi as a conventional hourglass to time his showdown with Omi. Unusually, in the following episode, Dashi tells Omi that they no longer had any time-travelling Shen Gong Wu.