  Existence of metastable quarks of new generation can be embedded into
phenomenology of heterotic string together with new long range interaction,
which only this new generation possesses. We discuss primordial quark
production in the early Universe, their successive cosmological evolution and
astrophysical effects, as well as possible production in present or future
accelerators. In case of a charge symmetry of 4th generation quarks in
Universe, they can be stored in neutral mesons, doubly positively charged
baryons, while all the doubly negatively charged "baryons" are combined with
He-4 into neutral nucleus-size atom-like states. The existence of all these
anomalous stable particles may escape present experimental limits, being close
to present and future experimental test. Due to the nuclear binding with He-4
primordial lightest baryons of the 4th generation with charge +1 can also
escape the experimental upper limits on anomalous isotopes of hydrogen, being
compatible with upper limits on anomalous lithium. While 4th quark hadrons are
rare, their presence may be nearly detectable in cosmic rays, muon and neutrino
fluxes and cosmic electromagnetic spectra. In case of charge asymmetry, a
nontrivial solution for the problem of dark matter (DM) can be provided by
excessive (meta)stable anti-up quarks of 4th generation, bound with He-4 in
specific nuclear-interacting form of dark matter. Such candidate to DM is
surprisingly close to Warm Dark Matter by its role in large scale structure
formation. It catalyzes primordial heavy element production in Big Bang
Nucleosynthesis and new types of nuclear transformations around us.
