  In order to examine a muon excess observed by the Pierre Auger Observatory,
detailed Monte Carlo simulations were carried out for primary protons, iron
nuclei and strangelets (hypothetical stable lumps of strange quark matter). We
obtained a rough agreement between the simulations and the data for ordinary
nuclei without any contribution of strangelets in primary flux of cosmic rays.
Our simulations suggest that the shower observables are dominated by details of
hadronic interaction models.
