World Heart

A world heart is the core of any sphere. Some originate from the direct will of a deity, but most seem to come about very spontaneously in a poorly understood process. As far as can be determined, a times a fracture will appear within the Mist, bringing it into contact with the Ether through which divine energy can seep. This energy mixes with the Mist and crystalizes into a world heart, which then rapidly converts the surrounding mist into a new sphere. Deities can forcefully create these rifts as manipulate the resulting world heart and sphere somewhat, but even for them it is an imperfect process likely to result in numerous deviations from the intended design.
What exactly governs when natural rifts form is not known. Phoenix have been known to be able to sense these rifts as they are about to happen, but this is on a very short timescale.
World hearts provides energy and life to the sphere that they form around them, allowing plants to grow, animals to flourish and so on. The exact conditions varies from heart to heart, with some providing more or less heat and light, which inevitably affects how the sphere turns out. Warmer world hearts tends toward warm desserts and colder world hearts usually has more snowy terrains, but these are far from guarantees.
Most world hearts change their light in a cyclical pattern. Most common is a warm, yellowish light that turns to a colder, white light. These periods of variant luminescence are called daylight and nightlight. However, some world hearts have more than two and many have different colors entirely.
The time it takes for the colors to cycle varies from world heart to world heart, though there is a curious relative synchronicity between them known as timelink.
While many beings are nourished by the light provided by a world heart, some creatures are directly born from it. The most well-known are roc, giant avians who harbor ingrown protective instincts for the world heart and jinn, magically potent beings with links to fire and color.
World hearts are very difficult to destroy, between the guardianship of rocs and its own near impenetrable composition. Despite these, they are not indestructible. After several eons, world hearts can burn out and fall apart on their own, and certain cataclysmic powers can likewise permanently damage or even destroy them. If a world heart dies out, the sphere that surrounds it will soon follow, as the Mist seeps in and undoes all there is, swallowing it back up into its own existence until nothing remains.

Manifestation

A world heart is a perfect crystalline sphere. Their colors is on average yellow for daylight and white of nightlight, but this is far from universale. Size varies, though rarely has a world heart been measured as less than thirty kilometres in circumference.

Type

Metaphysical, Divine