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, making them one of the oldest groups of animals on Earth. 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 creatures feed by filtering plankton and other small particles from the water using a specialized structure called a lophophore. Brachiopods are found in various marine environments, from shallow coastal waters to deep ocean floors, and they play a role in the ecosystem by contributing to the benthic community.