A ghost is a dark matter-composed plasma-based life form that originally existed in symbiosis with a human body, but decoupled from that corporeal form upon its death. Dark matter consists largely of a plasma of very high energy non-standard particles (sometimes of a different parity) - or "dark plasma". Non-standard particles are particles that are outside the physicists' Standard Model and which are included in dark matter - matter which is six times more prevalent in the known universe than ordinary matter. Two different substrates, plasma and carbon, gave rise to life. Plasma life forms, in fact, spurred the development of organic carbon-based life on Earth.