Metamagic
Metamagic is the name given to a powerful kind of magic, more powerful than conventional magic or psychic abilities, that is highly expandable. Unlike conventional magic which is limited by certain rules (such as being able to create fire only on objects that can burn,) Metamagic can allow you to create fire on any surface, mix it with ice, and whatnot.
History
The Metamagic Core was created centuries ago by an unknown man. He used the most powerful magic and psychic powers available at the time to create Metamagic, which was more powerful than any known magic. However, he created this magic so that he can use it for his own evil purposes, and was struck down in battle before he could fully utilize it.
When the Metamagic Core was created, he managed to hide it far away in another galaxy, where it would use Void Travel to supply him and his warriors with powerful magic. However, when he was struck down, the secret was lost to everyone. On Earth, no one uses magic anymore, and it is lost to the ages.
Metamagic Core
The Metamagic Core is the source of all Metamagic. After its creator was lost, the Core eventually became aware of its surroundings. It knew that people would wish to come and use its powers for great and terrible purposes, so sought to protect itself. In order to do this, it surrounded itself with earth, grass, trees, rivers, and oceans - vague recollections of what it recalled about Earth, and created the Metamagicia. However, everything was still made of magic.
The Metamagicia were created to live on the surface of the planet the Core had created, and to guard it from intruders and people who would use the powerful magic for any purpose.
Metamagicia
The Metamagicia are a race of people originating from the Metamagic Core. They are created entirely of Metamagic Energy, and take on the form of humanoid animals. The Metamagic Core had vague recollections of Earth, and created its protectors in the image of what it could remember. Humans, animals, but was there a difference between them?
Most (but not all) Metamagicia are humanoids with animal features.
Users of Metamagic
Metamagicia are created entirely of Metamagic, and so can utilize the various abilities therein. Other species can also utilize Metamagic, but they will slowly become more and more magic themselves. Their children will be more Metamagic than the previous generation, until they, too, are Metamagic. They'll also take on the humanoid-animal characteristics of standard Metamagicia.