Lithocytes are transported along the ciliary surface to build the statolith of ctenophores.

All organisms capable of locomotion possess equilibrium receptor systems that use the gravitational field as a reference. In aquatic invertebrates, gravity receptors (statocysts) are considered to be the earliest known sense organs. Statocysts are composed of a dense mass (statolith or statoconia) that loads and mechanically stimulates sensory receptors, which are commonly cilia.