  The algebraic elements of gravitational and Standard Model gauge fields
acting on a generation of fermions may be represented using real matrices.
These elements match a subalgebra of spin(11,3) acting on a Majorana-Weyl
spinor, consistent with GraviGUT unification. This entire structure embeds in
the quaternionic real form of the largest exceptional Lie algebra, E8. These
embeddings are presented explicitly and their implications discussed.
