Inside Mucrospirifer

brachiopods like Mucrospirifer were/are filter feeders, using a ciliated organ called a lophophore to filter edible particles from seawater. inside this broken brachiopod is what i believe to be a fossilized lophophore, or at least the calcareous brachidium that supported it.

i tried taking a pic of this months ago, but this time i feel like i did this fossil justice.
also on sale on ebay [link]