There are several proposed types of exotic matter:Hypothetical particles and states of matter that have not yet been encountered, but whose properties would be within the realm of mainstream physics if found to exist. Several particles whose existence has been experimentally confirmed that are conjectured to be exotic hadrons and within the Standard Model. States of matter that are not commonly encountered, such as Bose–Einstein condensates, fermionic condensates, nuclear matter, quantum spin liquid, string-net liquid, supercritical fluid, color-glass condensate, quark–gluon plasma, Rydberg matter, Rydberg polaron, photonic matter, Wigner crystal, superfluid and time crystal but whose properties are entirely within the realm of mainstream physics. Forms of matter that are poorly understood, such as dark matter and mirror matter. Ordinary matter that when placed under high pressure, may result in dramatic changes in its physical or chemical properties. Degenerate matter Exotic atoms