statolith

Etymology

From Ancient Greek στάσις (stásis, “standing”) +‎ -lith

Noun

statolith (plural statoliths)

1. A specialized form of amyloplast involved in graviperception by plant roots and most invertebrates.
   • 2002, David Randall, Eckert Animal Physiology‎, page 242:

     The statolith is either acquired from the animal's surroundings or secreted by the epithelial cells of the statocyst. A lobster, for example, loses its statoliths at every molt and replaces them with new grains of sand. In any case, the statolith must have a higher specific gravity than the surrounding fluid.