Statoconia are also sometimes termed a statocyst. Its structure and function resembles the statocyst of some animals. Octopuses may also use the statocyst to hear sound. The sensory organs include a statocyst and, in some groups, two unicellular ocelli. Called statospore, stomatocyst or statocyst, this structure is usually globose and contains a single pore. The statocyst is protected by a transparent dome made of long, immobile cilia. Some species of "Paracatenula" such as "P. galateia" possess a statocyst with a single statolith.