The Phylum Brachiopoda (“arm foots”) contains animals that are known as
lampshells. This is an ancient group that is well represented in the fossil
record (with some 30,000 described species) but only about 300 living species.
Brachiopods resemble bivalve molluscs, but unlike bivalves, they have shells
that are located on the ventral and dorsal side rather than left and right.
Brachiopods are divided into two classes based on whether they have shells that
are connected by a hinge with interlocking “teeth” or with shells of unequal
size. Brachiopods in the latter group are called lampshells because the larger
ventral valve resembles a Roman oil lamp. Some brachiopods attach themselves to
the substrate by a pedicel on the ventral valve while others just cement the
ventral valve to the substrate (like an oyster) or burrow into the sediment.
Like bryozoans, brachiopods also have a lophophore surrounding the mouth that is
used for feeding and gas exchange.