Temporal Heads are items that are extremely rare drops from Wither Skeletons. There is a very slim chance that the Wither Skeleton is mutated and appears blue and sparkly. The chance of this happening is as slim as a Wither Skeleton dropping its head, and the chance is doubled for a mutated one to drop a Temporal Head.
Temporal Heads can be worn so that time either speeds up or slows down for the Player, or they can be used along with Blocks of Quantum to create and fight a Quantum Wither. Temporal Heads are also throwable, but can be retrieved since they pop out as items when they hit something. Whatever it hits will cause a 4x4 block area to be surrounded by an aura that slows down time. You can tell where the aura is since it is a bluish half-circle (Circles made up of lots of little blocks) that makes whatever is inside it "wave" and be a blue hue. It lasts for about five minutes.