This calyx was found while sifting through matrix while looking for dis-articulated crinoid arms for another fossil. It is quite a find measuring a little over 3 cm in width and it has part of gastropod fossil (see arrow) located near the top of its folded up arms.
This crinoid appears to be a Pterocrinus acutus (Wetherby, 1879). The creature existed in the Mississippian Period and was found in the Glen Dean member of Grayson County Kentucky USA. This next image has 3 arrows highlighting the spines on the arms.
Side view of spines below.
Thanks to Kenny for the images.
See more images of crinoids like this at Don R. Chesnut's web page on fossils of the Sloans Valley Member (Paragon Formation).
