Chronosphere

The Chronosphere is a glowing, spinning, metallic sphere that allows the person who possesses it to travel the Ocean of Time to the past. It is located inside the chamber of the Grand Clock in Time's castle, as seen in Alice Through the Looking Glass.

Alice Through the Looking Glass
The Chronosphere is located inside the chamber of the Grand Clock in Time's castle. After being removed of its place, Alice used it to travel the Ocean of Time to the past to find out what was causing the Hatter to be more mad than usual.

Trivia

 * The word "chronosphere" is made of the union of the word "chrono", that means "time", referring to the object powers, and the word "sphere", referring to its shape.
 * The Chronosphere does not exist in Lewis Carroll's stories. It is an invention of screenwriter Linda Woolverton to allow the time travel plot of the film.