  In this paper we briefly discuss the problem of the origin of Ultra High
Energy Cosmic Rays in the framework of Top-Down models. We show that, for high
energy of decays and in a wide range of spectra of injected protons, their
extragalactic flux is consistent with the observed fluxes of cosmic rays in the
energy range 0.1 E_{GZK}< E < 10E_{GZK}. For suitable energy and spectra of
injected protons, the contribution of galactic sources is moderate, in this
energy range, but it dominates at smaller and larger energies. In such models
we can expect that at these energies the anisotropy of cosmic rays distribution
over sky will be especially small.
  Some possible manifestations of decays of super massive particles such as,
for example, primordial black holes with masses M_{pbh} ~ 10^{-5} g, are
considered. In particular, we show that partial conversion of energy released
during these decays at redshifts z ~ 1000 to Ly-alpha photons can delay the
hydrogen recombination and distort the spectrum of fluctuations of the cosmic
microwave background radiation.
