Can cosmic rays provide sign of strangelets?

We discuss the possible imprints of Strange Quark Matter (SQM) in cosmic ray data. In particular, we investigate the propagation of SQM through the atmosphere and discuss: i) direct candidates for strangelets, ii) exotic events interpreted as signals of SQM and iii) muon bundles and delayed neutrons in Extensive Air Showers. The physics and astrophysics of SQM is shortly reviewed. We point out the possibility that extreme energy cosmic rays are the results of the decay of unstable primordial objects. Finally, the abundance of possible candidates for strangelets and their mass spectrum are estimated and compared with the astrophysical limits and prospects of the possible observation of SQM in accelerator experiments are outlined.