  We construct a natural model of the supersymmetric SU(6) unification, in
which the symmetry breaking, down to the standard model gauge group, results in
the number of pseudo-Nambu-Goldstone superfields with interesting properties.
Namely, besides the Higgs doublet-antidoublet pair which is responsible for the
electroweak phase transition, the Nambu-Goldstone sector consists of multiplets
in the anti- and fundamental representations of SU(5). While being strictly
massless in the supersymmetric limit, they acquire the weak scale masses as a
result of its breaking. The color-triplet components of this light sector
could, in principle, mediate an unacceptably fast proton decay; however,
because of the natural $\text{TeV}/M_{\text{GUT}}$ suppression of the Yukawa
couplings to the light quarks and leptons, their existence is compatible with
the experimental bound on proton lifetime. This suppression is made further
interesting, since it results in the lifetime, of the lightest of the
above-mentioned colored particles from 1 sec to 1 day, long enough for it to
appear stable in the detector. Furthermore, we argue that the accommodation of
the color-triplet pseudo-Nambu-Goldstones, without fine-tuning or contradicting
observations, implies SU(6) unification.
