papilla
2. (Annelida: Hirudinoidea) In leeches, a small to large protrusible sensory organ; metamerically arranged or scattered on the dorsal surface; large papillae are called tubercules.
3. (Arthropoda: Crustacea) Small steep-sided prominences on the valve surface of Ostracods.
4. (Arthropoda: Insecta) A minute soft projection, a modified ligula of silk-spinning caterpillars.
5. (Brachiopoda) Fine spines either solid or hollow on the inside of the shell; endospines.
6. (Echinodermata) In holothurians and ophiuroids, tube foot with sensory function.
7. (Echiura) Wart-like or rounded tubercles on the surface of the body, maybe uniform over the surface, and are often associated with glandular cells.
8. (NEMATA) Pimple-like, simple sensory organs.
9. (Platyhelminthes: Trematoda) An accessory adhesive organ bearing a retractile tip.