  Particle physics candidates for cosmological dark matter are usually
considered as neutral and weakly interacting. However stable charged leptons
and quarks can also exist and, hidden in elusive atoms, play the role of dark
matter. The necessary condition for such scenario is absence of stable
particles with charge -1 and effective mechanism for suppression of free
positively charged heavy species. These conditions are realized in several
recently developed scenarios. In scenario based on Walking Technicolor model
excess of stable particles with charge -2 and the corresponding dark matter
density is naturally related with the value and sign of cosmological baryon
asymmetry. The excessive charged particles are bound with primordial helium in
techni-O-helium "atoms", maintaining specific nuclear-interacting form of dark
matter. Some properties of techni-O-helium Universe are discussed.
