In a chromonic, relatively flat molecules form linear aggregates. For aqueous solutions, the molecules have a flat core, such as a carbon ring system, with highly water-soluble side groups, such as a sulfonate or carboxyl. The molecules aggregate in linear stacks with the flat cores lying one on top of the other. The aggregates are continuously growing and shrinking. At low concentration, most of the molecules exist as isolated monomers. As the concentration increases, the average stack size begins to grow. At a sufficiently high concentration, the long stacks of molecules interfere with each other to form liquid crystals.