2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/51740We explain how structures related to octonions are ubiquitous in M-theory. All the exceptional Lie groups, and the projective Cayley line and plane appear in M-theory. Exceptional G_2-holonomy manifolds show up as compactifying spaces, and are related to the M2 Brane and 3-form. We review this evidence, which comes from the initial 11-dim structures. Relations between these objects are stressed, when extant and understood. We argue for the necessity of a better understanding of the role of the octonions themselves (in particular non-associativity) in M-theory.6 pages, iopart.sty, Presented at the the 24th International Colloquium on Group-Theoretical Methods in Physics. Paris, July 15-22, 2.002High Energy Physics - Theorytext