Casein micelles are supramolecule of colloidal size. They are modeled as having a lattice structure in which both casein-calcium phosphate aggregates and casein polymer chains act together to maintain its supramolecular integrity. The interlocked structure and occurrence of multiple interactions produce an open sponge-like particle that is generally resistant to spatial changes. The structural arrangement within the casein supramolecule can be modified by environmental changes that modify hydrophobic interactions and calcium phosphate solubility. This is discussed in relation to microstructure imaging using electron microscopy and changes that occur during acid coagulation, heating, and ethanol addition.