Treasure Chest are special containers in Freedom Planet. They are placed throughout every stage of the game. There are 3 Keystones inside each chest. The Element of the orbs you get will depend on the color of the crest on the chest upon opening (The crests change colour very fast). These chest can also be picked up and thrown by Milla.
Freedom Planet 2
Treasure Chests return in Freedom Planet 2. They are now bigger in size and contains more useful items such as Crystal Clusters and new inventory items such as soda bottles and potions (the purposes of these new items are currently unknown).