Yggdrasil — The World Tree

At the center of all Norse cosmology stands Yggdrasil — the great ash tree whose roots reach into three wells, whose branches hold nine worlds, whose bark shelters gods, men, giants, and dwarves. The eagle watches from its crown. The serpent gnaws at its roots. The squirrel Ratatoskr runs messages between them. Yggdrasil is the universe itself, alive and interconnected.

These signs carry the World Tree and the nine realms of Norse cosmology.