Balancing stone from inner ear. Coloured scanning electron micrograph (SEM) of crystals of calcium carbonate on the surface of an otolith. An otolith or otoconium is a calcified stone that is found in the otolith organs of the inner ear. They are attached to sensory hairs, and, when the head tilts, the stones' movement causes nerve impulses that allow a sense of balance and orientation to be maintained. In humans, otoconia range from 3-30 microns (millionths of a metre) across. Magnification unknown.