Demospongiae is a class of sponges that belong to the phylum Porifera. They are the largest class of sponges, comprising about 90% of all sponge species. Demosponges are primarily characterized by their skeletons made of silica or spongin, a fibrous protein. They can be found in various marine and freshwater environments. These sponges exhibit a wide range of shapes, sizes, and colors. Most Demospongiae are filter feeders, drawing water through their porous bodies to extract nutrients. They play a crucial role in aquatic ecosystems by providing habitat and contributing to nutrient cycling.