What is the X in X-mas?
Any of various marine invertebrate animals of the phylum Brachiopoda that resemble clams. Brachiopods have paired upper and lower shells attached to a usually stationary stalk and hollow tentacles covered with cilia that sweep food particles into the mouth. Brachiopods are probably related to the phoronids and bryozoans, and were extremely abundant throughout the Paleozoic Era.
any member of the phylum Brachiopoda, a group of bottom-dwelling marine invertebrates. They are covered by two valves, or shells; one valve covers the dorsal, or top, side; the other covers the ventral, or bottom, side. The valves, of unequal size, are bilaterally symmetrical; i.e., the right and left sides are mirror images of one another. Brachiopods (from the Greek words meaning "arm" and "foot") are commonly known as lamp shells because they resemble early Roman oil lamps.