Tiny hair like projections jutting from the top of the cell in bundles such as those residing in the cochlea.

Hair cells are sensory cells that react to mechanical stimuli and transmit information to the brain; they are the basic sensory unit of the inner ear.

Hair cells are the sensory receptors of both the auditory system and the vestibular system in all vertebrates. In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear. They derive their name from the tufts of stereocilia that protrude from the apical surface of the cell, a structure known as the hair bundle, into the scala media, a fluid-filled tube within the cochlea.