After the helium nucleus He-4, the oxygen nucleus O-16 is the second stable one in Nature and the first upper-order nucleus. Its structure is based on the successive conversions of lithium Li-6, lithium Li-7, beryllium Be-9, boron B-10, boron B-11, carbon C-12 and nitrogen N-14 into oxygen nucleus O-16. From this first upper-order nucleus the second one is constructed (calcium nucleus Ca), from the second the third one (tin nucleus Sn) and from the third the fourth one (orion nucleus Or-307), 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. It is noted that, this orion nucleus Or-307 with a differential atomic number Z=125 (unified theory of dynamic space) is the corresponding "hypothetical unbihexium Ubh", whose atomic number is Z=126 (Nuclear Physics). However, the number Z=125 looks symmetrical and not magical at all, due to the 2.5 factor.