What is "otolith"

Otolith \O"to*lith\, Otolite \O"to*lite\, n. [Oto- + -lith, -lite.] (Anat.) One of the small bones or particles of calcareous or other hard substance in the internal ear of vertebrates, and in the auditory organs of many invertebrates; an ear stone. Collectively, the otoliths are called ear sand and otoconite.

n. (context zoology English) A small particle, comprised mainly of calcium carbonate, found in the inner ear of vertebrates, being part of the balance sense.

An otolith (οτο-, oto-, ear + λιθος, lithos, a stone), also called statoconium or otoconium or statolith, is a structure in the saccule or utricle of the inner ear, specifically in the vestibular labyrinth of vertebrates. They have been identified in both extinct and extant vertebrates. Counting the annual growth rings on the otoliths is a common technique in estimating the age of fish. The saccule and utricle, in turn, together make the otolith organs. They are sensitive to gravity and linear acceleration. Because of their orientation in the head, the utricle is sensitive to a change in horizontal movement, and the saccule gives information about vertical acceleration (such as when in an elevator).