  There have been several reports of exotic nuclear fragments, with highly
unusual charge to mass ratio, in cosmic ray experiments. Although there exist
experimental uncertainties which make them, at best, only candidate "exotic"
events, it is important to understand what they could be, if they are
eventually confirmed. Among other possible explanations, some authors have
interpreted them to be lumps of strange quark matter (strangelets). A major
problem with such an interpretation is that to reach the earth's surface, they
must possess an unusually high penetrability through the terrestrial
atmosphere. We show that a recently proposed mechanism for the propagation of
strangelets through the earth's atmosphere, together with a proper account of
charge capture and ionisation loss, would solve this problem. We also argue
that this could lead to viable strategies for definitive detection of strange
quark matter in cosmic ray flux using a ground based large area array of
passive detectors.
