Yggdrasil, the tree of life (Norse mythology). Its many roots and limbs keep all the different worlds together: Asgard, Midgard, Helheim, Niflheim, Muspellheim, Svartalfheim, Alfheim, Vanaheim and Jotunheim. Below its roots there is the spring that fills Mimisbrunnr, the well of wisdom, guarded by Mimir.
The agate is found in volcanic rocks. It is characterized by a series of concentric bands of similar colors, opaque and translucent, which recall the cutting a tree trunk. The name 'Agate' comes from the river Achates, south of Sicily, Italy, where he says he found the first of these stones. Agate was highly revered by the ancients and was regarded as the stone of science. Also attributed healing powers against diseases eyes or against spider bites and scorpion stings. In Saudi eyes were used as images of the gods. Also found in the eye sockets of mummies of ancient Egypt. In Islam, agates are also very precious stones. According to tradition, a ring of agate, for example, protects the wearer from some mishaps and guarantee longevity, among other benefits.