Noun, pl. statoliths
1. Any of the usually calcareous bodies suspended in a statocyst. (merriam-webster.com)
1. Any of various starch grains or other solid bodies in the plant cytoplasm that are held to be responsible by changes in their position for changes in orientation of a part or organ (merriam-webster.com);
2. A sand grain or a structure of calcium carbonate or other hard secreted substance, found in the cavity of a statocyst. It stimulates sensory cells lining the cavity with which it comes in contact under the influence of gravity.(biology-online.org)
3. A calcareous particle in the statocysts of invertebrates that stimulates sensory receptors in response to gravity, so enabling balance and orientation. (Google Dictionary)
1. A specialized form of amyloplast involved in graviperception by plant roots and most invertebrates (wiktionary.org).
2. A type of amyloplast found in root tip cells of higher plants. It can sediment within the cell under the influence of gravity and is thought to be involved in the detection of gravity in geotropism (biology-online.org).