Crystals often appear in very regular and nonetheless naturally evolved structures. One of many of the reasons for this phenomena is a very regular arrangement of the atoms which comprise a crystal lattice. For example, chlorine and sodium atoms in a saline solution (NaCl) create a kind of three dimensional chess board pattern. This is furthermore responsible for the creation of cubic crystal structures.
In the visualisation, one can observe several typical atomic lattices (Saline solutions, diamond, sphalerite...).