Chest of Harmony



The mysterious chest is a chest first seen in the second part of season four's premiere, after emerging from the Tree of Harmony. The chest requires six keys to open, and its contents are unknown.

Princess Twilight Sparkle - Part 2
After the chest emgerges from the Tree of Harmony, Princess Celestia reveals that she does not know the location of the keys, but says to Twilight Sparkle "...it is a mystery you will not be solving on your own."