Polymerization of simple molecules into extended structures with unexpected features is possible at high pressure, where intramolecular bonding and intermolecular contacts can become indistinguishable. Color images of the structures of water and carbon dioxide at high pressure are available in this issue of JCE Online. In the case of water, a face-centered cubic array of oxygen atoms forms the basis of the proposed "symmetric ice" H₂O-X, a polymorph of solid H₂O in which the hydrogen bonds are the same length as the covalent O-H bonds. For carbon dioxide, the helical arrangement of CO₄ tetrahedra is the dominant structural motif of quartzlike carbon dioxide, proposed as a new high temperature, high pressure phase of CO₂.