Fossilized brachium from a brachiopod
The spiral-shaped object in this fossil brachiopod is called a brachidium. In life it supported a feathery organ called a lophophore that the animal used to collect food by filtering plankton from seawater. Although brachiopods are among the most common of fossils, those with brachia preserved are quite rare. Hanover, Indiana, USA.
Copyright ©Mark Steinmetz