Crinoids are also known as sea lilies or feather stars. These marine animals are echinoderms and are closely related to starfish and sea urchins. The term crinoid is derived from the Greek word "krinon," which means lily. They are also referred to as stalked crinoids because of their long stems that attach to surfaces on the ocean floor. These stems are composed of small plates called ossicles and are often used to anchor the crinoids to rocks or other solid surfaces. Collectively they are known as crinozoans, and many species have been identified over the years, making them a fascinating subject of study for marine biologists.