Roots of Unity

Small wooden discs about 2 1/4 inches in diameter and between 5 and 10mm thick (see below). They are rumoured to be made from the roots of the great tree Unity that supports the centre of the world. They are made of a fine-grained dark-golden wood, and are all exactly identical. They are symmetric if cut in half down the edge (i.e. in to two thinner circles).

The most noticeable features about the roots is their pattern of thickness. The discs are not of the same thickness across their whole surface, giving a rippled, contoured effect. The exact thickness of the disc in any place is as follows:
Holding the disc vertically, an infinitesimally thin line joining the top to the middle will be 5mm + 5mm thick. The line joining the point halfway round from this (i.e. the bottom) to the middle is 5mm + 2.5mm thick. The two lines joining the points 1/3 and 2/3 of the way around to the centre are 5mm + 5/3mm thick. The line joining the four points 1/5 of the way round are 5mm + 5/5mm (i.e. 5mm + 1mm) thick. This continues so that the lines joining the middle to a point (1/n) of the way around is (5 + 5/n)mm thick, where n is every prime number from 2 to infinity. The thickness of the disc thus varies infinitely quickly from point to point, but still appears smooth.

The discs are extremely common in the land (there are more discs than people). A farmer ploughing a field will typically upturn several dozen. They are almost unbreakable and practically impossible to chip or carve and will only burn in a very intense fire. They have no apparent use or magical properties whatsoeverl however, they are widely used as good-luck charms. Almost any house would have several over the doorway, on mantle pieces etc. and people frequently carry them on their person. Folk lore says that the discs are made from the roots of the great tree Unity, the tree that supports the centre of the world. Whether this is true or, if not, what the truth is, is unknown.

Magical Properties: