Endohedral metallofullerene molecules of the type Nd@C-82 were deposited on thin films of C-60 and investigated with an ultrahigh vacuum scanning tunneling microscope (UHV-STM). The as-deposited Nd@C-82 are observed to form well-ordered two-dimensional close-packed structures. These structures are transformed to very stable ring-shape clusters of (Nd@C-82)(n) after they experienced a strong electric field of the scanning. The ring-shape clusters have a shape of a hexagonal polygon, consisting of either 6 or 12 molecules, and this points to the formation of covalently bonded Nd@C-82 supramolecules.