Coloured scalar quarks which are present in some theories (e.g. SUSY QCD) produce a new family of hadrons. Some of these new hadrons could be absolutely stable and could be produced and preserved up to now in the course of cosmological expansion. We derive constraints on the properties of such hadrons imposed by the results of the searches for various exotic particles in the terrestrial matter and discuss an alternative experimental approach to such searches which might be more successful. © 1984 Società Italiana di Fisica.