  I describe a dark matter candidate based in qcd physics in which the dark
matter is composed of macroscopically large "nuggets" of quark and anti-quark
matter. These objects may have a sufficiently massive low number density to
avoid constraints from direct detection searches. Though not "baryonic" in the
conventional sense quark matter is strongly interacting and will produce a
clear signal in ground based detectors. As the prospects of detecting these
objects are mainly limited by the detector cross-section large scale cosmic ray
detectors are a promising search platform. To this end I describe the basic
properties of the air shower induced by the passage of a quark nugget through
the earth's atmosphere. It will be shown that this shower is similar in several
important ways to the shower induced by a single ultrahigh energy cosmic ray.

High Energy Astrophysical Phenomena