  Mirror matter is a self-collisional dark matter candidate. If exact mirror
parity is a conserved symmetry of the nature, there could exist a parallel
hidden (mirror) sector of the Universe which has the same kind of particles and
the same physical laws of our (visible) sector. The two sectors interact each
other only via gravity, therefore mirror matter is naturally "dark". The most
promising way to test this dark matter candidate is to look at its
astrophysical signatures, as Big Bang nucleosynthesis, primordial structure
formation and evolution, cosmic microwave background and large scale structure
power spectra.
