  Searching for strangelets in cosmic rays may be the best way to test the
possible stability of strange quark matter. I review calculations of the
astrophysical strangelet flux in the GV--TV rigidity range, which will be
investigated from the Alpha Magnetic Spectrometer (AMS-02) on the International
Space Station, and discuss the merits of strangelets as ultra-high energy
cosmic rays at EeV--ZeV energies, beyond the Greisen-Zatsepin-Kuzmin cutoff. I
also address some ``counter-arguments'' sometimes raised against the
possibility of stable strangelets. It will be argued that stability of strange
quark matter remains a viable possibility, which must be tested by experiments.
