statoconia

On top of this layer lie calcium carbonate crystals called statoconia or otoliths.

In parts of these semi circular canals, specifically the maculae, calcium carbonate crystals known as statoconia rest on the surface of this gelatinous material.

The gelatinous layer and the statoconia together are referred to as the otolithic membrane, where the tips of the stereocilia and kinocilium are embedded.

When the head is tilted such that gravity pulls on the statoconia the gelatinous layer is pulled in the same direction also causing the sensory hairs to bend.

After the death and decomposition of a fish, otoliths and statoconia may be preserved within the body of an organism or be dispersed before burial and fossilization.

The macula is also sensitive to linear acceleration as the inertia possessed by the statoconia can also shift the gelatinous layer during increases and decreases in linear velocity.

Statoconia (also called otoconia) are numerous grains, often spherical in shape, between 1-50 microns; collectively, statoconia are also sometimes termed a statocyst.

Both statoconia and otoliths are used as gravity, balance, movement, and directional indicators in all vertebrates and have a secondary function in sound detection in higher aquatic and terrestrial vertebrates.

However, when the head is tilted, the pull of gravity on statoconia shift the hair cell processes to the side, distorting them and sending a message to the central nervous system that the head is no longer level but now tilted.