Here is a neat crinoid stem that my cousin found while at Lake Cumberland, Kentucky. It is a Mississippian period crinoid stem with a small...

Here is another crinoid disc showing the center of the stem. I think the center is an agate since you can see layers in it. This specimen ca...

Here is the inside view of a Mississippian crinoid from Lake Cumberland. It is neat to see the disc segments and inside stem column.