Brachiopods are marine animals with hard shells that resemble clams but are not closely related. They belong to the phylum Brachiopoda and have existed for over 500 million years. Brachiopods typically have two shells, or valves, that are different in size and shape, and they are anchored to the sea floor by a stalk. These organisms primarily feed by filtering plankton and other small particles from the water using a specialized structure called a lophophore. Brachiopods are found in various ocean environments, from shallow waters to deep sea, and they play a role in the marine ecosystem as both filter feeders and prey for other animals.