Answer the following question given this paragraph: While almost all echinoderms live on the sea floor, some sea-lilies can swim at great speeds for brief periods of time, and a few sea cucumbers are fully floating. Some echinoderms find other ways of moving. For example, crinoids attach themselves to floating logs, and some sea cucumbers move by attaching to the sides of fish. Q: Sea-lilies, sea cucumbers and sea stars fall into what class of organism? Choices: - snakes - mollusks - crabs - echinoderms A:
echinoderms