Two polygons are said to be linked if they share an edge; two polyhedra are linked if they share a face. Regular polygons or polyhedra of the same size are linked sequentially to form chains. A chain may twist and curl back to link to a previous figure, forming a closed loop. Regular polygons and cubes can form loops. Chains of ocatahedra, tetrahedra, dodecahedra, or icosahedra, no matter how long, can never form a closed loop.
