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 the 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 a scenario based on the 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.

The modern theory of universe, based on general relativity, has evolved the triumph of Einstein's ideas by putting the cosmological term which was first introduced by Einstein (1917), in the `standard' λ CDM model. The corresponding dark energy is the dominant element of the modern universe, maintaining 70% of its total density.

General relativity and dark energy maintain the frame for the portrait of elementary particles in the universe. To survive in the universe, the particles composing the visible matter should be stable as are nuclei and electrons. However, one must also explain the modern dark matter density, corresponding to 25% of the total density and exceeding the baryonic matter density by a factor of five. The widely shared belief is that dark matter is nonbaryonic and consists of new stable particles.

For a particle with mass m, the particle physics time scale is t ~1/m (here and further, if not indicated otherwise, we use the units h= c = k =1), so in particle world, we refer to particles with lifetime τ1/m as to metastable. To be of cosmological significance, metastable particle should survive after the temperature of the universe T fell down below T ~ m,which means that the particle lifetime should exceed t ~(m_Pl /m).(1/m). Such a long lifetime should find reason in the existence of an (approximate) symmetry. From this viewpoint, cosmology of dark matter is sensitive to the most fundamental properties of microworld, to the conservation laws reflecting strict or nearly strict symmetries of particle theory.

Physics Journal, Stable particles, Dark matter, Baryon Asymmetry, Walking Technicolor, Anomalous Isotopes, Ultra High Energy Cosmic Rays, UHECR, Tera-Fermion Mass Pattern, Dirac Mass Generation, Leptons, AC-Fermions, baryosynthesis, Chromo-Coulomb Binding Energy.