  Stable Superstring Relics (SSR) provide some of the candidates for the
possible origin of the Ultra High Energy Cosmic Rays (UHECR). After a brief
overview of the motivations for introducing such relics, we address the
question whether statistical fluctuations in the formation of the air showers
generated by the primary spectrum of protons can be separated from a possible
signal of new physics hidden in the first impact with the atmosphere. Our
results are generated by using minimal modifications in the cross section of
the primaries, and using available simulation codes used by the experimental
collaborations. The results indicate that substantial increases in the cross
section of the first impact, possibly due to new interactions, are unlikely to
be detected in geometrical and/or variations of multiplicities in the cascade.
