The study of hard tissues from mammals (e.g. bone and teeth) and from other animals (e.g. shells and exoskeletons of crustaceans) is largely based on physical-chemistry characterization techniques. Among these techniques, Electron Microscopy (SEM and TEM), diffraction techniques and, more recently, Focused Ion Beam (FIB) have been offering answers to fundamental questions about the nature, origin and function of these biological materials. Our current focus is on mineralised tissues in reptiles.