The triquetra is a knot-like formation with three ends, commonly shown interlaced around a circle. The symbol is also known as the symbol of charm, and is used in the depiction of several norse and scandaninavian items such as the Mjölnir.
The Triquetra was heavily used by Norse pagans, as they used articles like pendants resembling the Mjolnir with a Triquetra symbol crafted on it.
The Mjölnir is Thor's hammer. The symbol is used for protection.
The Valknut is a symbol of Odin.
The Nine Worlds
The Yggdrasil connecting the nine realms.
In Norse mythology, the nine worlds also known as nine realms, are planets or massive city-like places located throughout the cosmos, connected by the world three known as Yggdrasil. The interdimensional rainbow-like path known as Bifröst, bridges Asgard with other realms.