Triqueta.

The Triquetra, also known as the Trinity Knot, is a significant Celtic symbol.

It's often depicted as three interconnected arcs or loops, forming a triangle-like shape.

In Celtic Paganism and Witchcraft/Wicca, it symbolizes interconnectedness and the cycle of life, death, and rebirth, representing the three realms (earth, sea, and sky) or the Triple Goddess (Maiden, Mother, Crone).

The symbol is also used in Christianity to represent the Holy Trinity.

The number of Three itself is also important, numerology-wise.