Clusters of metallic elements with valence electron counts 2, 8, 18, 20, ... are known to be stable with filled electronic shells and large gaps between shells. Through first principles theoretical studies of TMCa8 (TM = Sc, Ti, V, Cr, Mn, Fe, Co, ...) clusters we identify a stable magnetic FeCa8 cluster of 24 valence electrons distributed into a closed 1S(2) 1P(6) 1D(10) 2S(2) shell sequence and with four electrons occupying the majority 2D(xy), 2D(x2-y2), 2D(xz) and 2D(yz) levels while the unfilled 2D(z2) level is separated by a large energy gap of 0.61 eV arising from atomic deformation and exchange splitting. (C) 2012 Elsevier B.V. All rights reserved.