This crinoid calyx was recently cleaned using a sand abrasive technique. The cleaning revealed a small holdfast at the base of the crinoid cup. I would interpret this as the crinoid cup had broken away from the stem and turned upside down on the sea floor. It had beent there awhile as small holdfasts including one shown below began attaching themselves to the cup. It appears to have been at least 7 crinoid or byrozoan holdfasts. Two near the cup base of the stem might be small Eucalyptocrinus holdfasts. Since the holdfasts were small the fossil got buried pretty quickly thus causing everything to fossilize.
The details show up better when the fossil is wet so I might polish it for better visualization of the plates.
The fossil cup was found in the Waldron Shale of Cheatham County, Tennessee, USA sometime in the 1960s. It was identifed as a Silurian Period Eucalyptocrinus magnus.
Thanks to Kenny for letting me use the cleaning equipment.