[ossicle] A paxilla (plural. paxillae) is a small umbrella-shaped structure sometimes found on Echinoderms, particularly in starfish (class Asteroidea) such as Luidia, Astropecten and Goniaster that immerse themselves in sediment. They are ossicles composed of calcite microcrystals found on the aboral (upper) surface of the animal. Their st...