The idea of designing unprecedented materials made of superatomic building blocks, motivated the present study on endohedral M@C20H20 (M = Li, Na, Mg+) species. Ground and excited electronic structures of M@C20H20 (M = Li, Na, Mg+) were analyzed by means of high-level quantum calculations. In their ground states, one electron occupies a defuse superatomic s-orbital that lies around the C20H20 cage. These entities populate higher angular momentum p-, d-, f-, g-superatomic orbitals in their low-lying electronic states. The proposed superatomic Aufbau shell model for Li@C20H20 and Na@C20H20 is 1s, 1p, 1d, 2s, 1f, 2p, 2d, 1g, 2f slightly different from that of Mg@C20H20+ which is 1s, 1p, 1d, 2s, 1f, 2p, 2d, 1g, 3s, 2f, 2g, 3p. These introduced superatomic orbital series resemble the Aufbau principle of solvated electron precursors.