  Assuming existence of (very) heavy fourth generation of quarks and antiquarks
we argue that antibaryon composed of the three heavy antiquarks can be light,
stable and invisible, hence a good candidate for the Dark matter particle. Such
opportunity allows to keep the baryon number conservation for the generation of
the visible baryon asymmetry. The dark matter particles traveling through the
ordinary matter will annihilate with nucleons inducing
proton(neutron)-decay-like events with ~5GeV energy release in outcoming
particles.
