Otoliths. Coloured scanning electron micrograph (SEM) of crystals of calcium carbonate on the surface of a mammalian otolith organ. 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 movement of the stones causes nerve impulses that form the basis of the sense of balance and linear acceleration. In humans, otoconia can range in size from 3-30 microns. Magnification: x2250 when printed at 10 centimetres wide.