The Unity are a crystalline entity, which live on P3X-562. They are a peaceful race, however, they are energy based, and can be dangerous for humanoids. Touching the unity can cause the unity to give of energy which can kill. The Unity lived in peace, until one day the Goa'uld came exploring through the Stargate. When the Goa'uld touched the Unity, he was killed, and so all the Unity were gathered in one place and killed. Although, physical death does not mean the same to the Unity as it does to humans. However, the Unity have the ability to take any shape or form that they desire, but being energy based, require the planets magnetic fields to stay stable, moving to another planet would lead to the eventual breakdown of the Unity releasing dangerous levels of radiation.