  Cubic double perovskites that host heavy ions with total angular momentum J =
2 can exhibit a singular magnetic state epitomized by a lone octupole and bulk
ferro-type magnetism. It exists in the Chen - Balents Hamiltonian with a
quadrupole interaction and competing exchange forces between the ions. Our
symmetry inspired analysis mirrors the Dzyaloshinskii - Man'ko theory of latent
antiferromagnetic ordering, and a 3-k collinear structure. Experimental tests
of the singular state include neutron and x-ray Bragg diffraction.
