A phylum of invertebrate animals often grouped with two other phyla under the name "Lophophorates." General characteristics include: a pair of protective shells (giving them a superficial resemblance to the bivalves - i.e. clams), a stalk protruding from the rear called a "pedicle" which anchors the animal to the sea floor, and a lophophore (a ridge with many tiny tentacles on it, used to catch food particles floating by). Brachiopod shells come in many different shapes and sizes. Brachiopods were extremely abundant during the Paleozoic era (both in terms of numbers of individuals and numbers of species), but were practically wiped out around 300 million years ago during the Permian mass extinction. Compare gastropod