The structure of the nuclei begins with the so-called lower-order nuclei, as the deuterium, tritium and helium He-3, which evolve into helium nucleus He-4 and then first upper-order oxygen nucleus O-16. The second upper-order calcium nucleus Ca is based on the fundamental natural phenomenon of mirror symmetry, by repetition of the first upper-order oxygen nucleus and one half of it, i.e. at the 2.5 factor. The same stands with the third upper-order tin nucleus Sn, which emerged from the second upper-order calcium nucleus, according to the mirror symmetry and the same 2.5 factor. Furthermore, orion nucleus Or-307 forecast, as a theoretical construction, is derived by repetition of the third upper-order tin nucleus and one half of it for the connection as the fourth upper-order nucleus, according to the mirror symmetry. The atomic numbers Z of the above four upper-order nuclei are the so-called four magic numbers, i.e. Z1=8, Z2=8x2.5=20, Z3=20x2.5=50 and Z4=50x2.5=125. That is the simple and elegant structure model, according to which the nuclei consist of fixed helium nuclei He-4 (plus deuterium, tritium and helium He-3, all evolving into helium He-4) and neutrons rotating around of them. It is noted that the word orion comes from the Greek όριον, meaning the limit. Thus, orion nucleus Or-307 means the limited nucleus of Nature that cannot be further divided, due to the indivisible original deuterium. Additionally, orion nucleus Or-307 is the corresponding hypothetical chemical element with atomic number Z=126 and placeholder symbol Ubh (Ubh-310 or Ubh-354), also known as element 126 or eka-plutonium.