MerKaBa, the 8 pointed Tantric Star, is one of the Crystalline Light Body Shapes. Merkaba meaning "Mer"=Light. "Ka"=Spirit. "Ba"=Body. It's basically a Stellated Octahedron (a Star Tetrahedron with an Octahedron in the center).
The Tantric Star is formed by interlocking ascending and descending tetrahedrons, functioning as a 3-dimensional mandala, connecting us to our centre point, a stargate into the matrix of manifest reality.
The Merkaba, or Tantric Star, consists of two equally sized interlocking tetrahedra triangles where one points up & the other down representing the God/Goddess, Yin/Yang the divine masculine & divine feminine in Tantric union. It is believed that by meditating upon the merkaba & by wearing it as a sacred charm, a doorway to higher levels of consciousness develops.