A snapshot of a hexatic membrane with its characteristic dislocations (yellow-blue dimers). Any sufficiently flexible elastic membrane with finite bond energies will melt via the formation of such dislocations to create a fluctuating analog of a bond-orientationally ordered planar hexatic. Mark Bowick, Chapter 11 in "Statistical mechanics of Membranes and Surfaces," ed. by D.R. Nelson, T. Piran, and S. Weinberg (World Scientific, Singapore, 2004).

Image courtesy of Dr. K. Anagnostopoulos, National Technical University of Athens.