Valknut.. the viking warrior symbol for protection. 9 points of the triangles each stand for one of the 9 viking noble virtues. (Honor, Courage, Perseverance, Fidelity, Self-Reliance, Industriousness, Truth, Hospitality & Discipline) The three triangles also stand for mind, body and spirit. Triangles also represent change. I couldn't be more obsessed with my first of many tattoos.
In Norse mythology, the World Tree called Yggdrasill runs like a pole through this world and the realms above and below it. Yggdrasill is a great ash tree that connects all living things and all phases of existence.