The Heart of Ymir is the very foundation of the world of Midgard itself. Hundreds of years ago, Odin slew Ymir and used fragments of the giant's heart to create Midgard. The fragments maintain Midgard's integrity and feed its growth. Each fragment is mostly hidden. According to General Spiegel, a fragment of the heart has the ability to grow into a whole heart. This means that every fragment that has been scattered throughout the world has the potential to become a full heart. In addition, once a year a beam of light emits from the heart and links all the other shards (or hearts).