The Brain Cell* is a "Sphere of the Emotions" containing a cube called the "Information Storage Block". Inside are 24 "Rods of Association" which light up when the "Tetrahedronal Light Muscle" (also inside) flexes. Usually this light power comes from the "Cosmic Juice Stations" at the corners of the cube. But when the pearl is formed at the point of consciousness, the Pineal gland lighthouse picks up the pearl light, broadcasts it. There is "redoubling light."
The pearl-making light slows down the Tetrahedral Light Muscle. The redoubling light builds up on its surfaces. If this is continued, the overload must be released. When the light load exceeds the capacity of the TLM, the Brain Cell expands.
Funicula is initiated to the vision of the "Haptihedron" by Amerindian guides. Her inner eye is opened. The octahedron inside the double tetrahedron of the Light Muscle appears expanded around her. Later, she realizes how the six sides of the cube are connected to the triangle corners to finish the shape.
The Haptihedron is the most universal shape--the most transitional. It's the structure of consciousness of beings of the metagalaxy. It becomes a generator and it is the first step in transformation.
The expanded Brain Cell is especially telepathic since its intensified light is not stepped down in rods, associations, memories, and so on.
Funicula reviews the energies involved in this expansion. It's not clear if the original Brain Cell loses its shape or gets additions. The light sources brought to meditation are important. Greeting light-bearing spirits from the center of the galaxy, Sirius, and Crux helps. In pearl making, the incoming breath of the spirit is united with the upsurge of sexual energy.
This union of "sky" (bird, lightning) with "earth" (snake, spiral) energies, combined with spiritual gathering and concentrating of light is the basis for building the Light Body.
* These models are organizing patterns of consciousness that are specialized in Brain Cells for information processing and in blood for cell development. The original Light Body book has a model of a Haptihedron Brain Cell for construction. Here it is separate.