I describe a possible role of the chiral anomaly and of a corresponding axion in understanding the origin of primordial magnetic fields in the universe. A possible five-dimensional origin of the axion is sketched. In passing, I comment on the role the axion plays in relativistic Magneto-Hydrodynamics. I then speculate on the role axions may play in solving the mystery of dark energy and of the matter-anti-matter asymmetry in the universe.
