  We show that grand unified theories based on SO(10) generate quite naturally
baryon number violating dimension seven operators that violate (B-L), and lead
to novel nucleon decay modes such as n \to e^-K^+, e^- \pi^+ and p \to \nu
\pi^+. We find that in two-step breaking schemes of non-supersymmetric SO(10),
the partial lifetimes for these modes can be within reach of experiments. The
interactions responsible for these decay modes also provide a new way to
understand the origin of matter in the universe via the decays of GUT scale
scalar bosons of SO(10). Their (B-L)-violating nature guarantees that the GUT
scale induced baryon asymmetry is not washed out by the electroweak sphaleron
interactions. In minimal SO(10) models this asymmetry is closely tied to the
masses of quarks, leptons and the neutrinos.
