Cosmic-Ray Extremely Distributed Observatory (CREDO) enables a strategy for a global analysis of cosmic-ray data to reach the sensitivity to extremely extended cosmic-ray phenomena, we call them super-preshowers, invisible for individual detectors or observatories. So far, the cosmic-ray research has been oriented on detecting single air showers only, while the search for ensembles of cosmic-ray events induced by super-preshowers is a scientific terra incognita. We aim at exploring this uncharted realm. Observation of super-preshowers would have an impact on cosmology, fundamental particle interactions, ultra-high energy astrophysics. You are welcome to join us!