Dark matter from encapsulated atoms
  We propose that dark matter consists of collections of atoms encapsulated inside pieces of an alternative vacuum, in which the Higgs field vacuum expectation value is appreciably smaller than in the usual vacuum. The alternative vacuum is supposed to have the same energy density as our own. Apart from this degeneracy of vacuum phases, we do not introduce any new physics beyond the Standard Model. The dark matter balls are estimated to have a radius of order 20 cm and a mass of order $10^{11}$ kg. However they are very difficult to observe directly, but inside dense stars may expand eating up the star and cause huge explosions (gamma ray bursts). The ratio of dark matter to ordinary baryonic matter is estimated to be of the order of the ratio of the binding energy per nucleon in helium to the difference between the binding energies per nucleon in heavy nuclei and in helium. Thus we predict approximately five times as much dark matter as ordinary baryonic matter! 
C.D. Froggatt and H.B. Nielsen