👉 Corystoidea is a group of marine invertebrates that include cephalopods, such as the sea cucumber and clams. They are characterized by their long, slender bodies with smooth surfaces and strong, flexible appendages called tentacles. Some corystoids have an internal cavity or gills for respiration, while others lack these structures. These animals play important roles in marine ecosystems through feeding on plankton, cleaning seafloor sediments, and aiding in the decomposition of
