The Charpactin are a xenos species of sentient fungoids who communicate entirely in bursts of ultraviolet colour.
These strobing emanations prove surprisingly effective at subduing and transfixing living beings, rendering them docile and amenable.
When Water Caste diplomats from the Fifth Sphere Expansion Fe'saan Sept encountered them, the T'au quickly negotiated a client-state treaty, drafting many of these creatures into their growing Edification Corps which was intended to maintain the loyalty of the Fire Caste to the Ethereals.
- Codex: T'au Empire (8th Edition), pg. 39