Sprites

A creature with the power to pop in and out of our reality at will. They are about the size of a melon, round and furry, and they can hover a small distance above the ground. Not much is known by the people of the world about sprites, as their ability to vanish at will makes them almost impossible to study. What is most well known is their system of equivalent exchange, studied by Witches for use in Sprite Indenture. Sprites are seemingly able to understand all languages, although they do not speak at all, they do make small noises, suggesting they have a voice box. They use this understanding to form contracts. It is unknown how sprites are able to fulfil contracts, but the most common theory is that they can somehow manipulate probability. This would make them as powerful as Gods, and yet they seem to only use this power in contracts with humans. Molecular study of sprite fur samples proves even more confusing, as they seem to have very little in common with life as it is commonly understood, they have no DNA or RNA, and the basic composition of their cells is not understood at all. All fur samples on earth vanished at some point, although no one can remember when it happened, and no written data appears to exist documenting this event.