Balancing stone from inner ear. Coloured scanning electron micrograph (SEM) of crystals of calcium carbonate (blue) 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 (not seen) and when the head tilts the stones move and trigger nerve impulses that allow balance and orientation to be maintained. In humans, otoconia range from 3-30 microns (millionths of a metre) across. Magnification unknown.