Ge.*

We report the magnetic structure and spin excitations of Mn₃Ge, a breathing kagome antiferromagnet with transport anomalies attributed to Weyl nodes. Using polarized neutron diffraction, we show the magnetic order is a k = 0 co-planar state belonging to a Γ₉ irreducible representation, which can be described as a perfect 120° anti-chiral structure with a moment of 2.2(1)μB/Mn, superimposed with weak collinear ferromagnetism. Inelastic neutron scattering shows three collective Q = 0 excitations at Δ₁= 2.9(6) meV, Δ₂ = 14.6(3), and Δ₃ = 17.5(3) meV. A field theory of Q ≈ 0 spin waves in triangular antiferromagnets with a 120° spin structure was used to classify these modes. The in-plane mode (α) is gapless, Δ₁ is the gap to a doublet of out-of-plane spin excitations (βx,βy), and Δ₂, Δ₃ result from hybridization of optical phonons with magnetic excitations. While a phenomenological spin Hamiltonian including exchange interactions, Dzyaloshinskii-Moriyainteractions, and single ion crystal field terms can describe aspects of the Mn-based magnetism, spin wave damping (Γ = 25(8) meV) and the extended range of magnetic interactions indicate itinerant magnetism consistent with the transport anomalies.