Sorry new at this I had a description I thought. I found it while arrowhead hunting in Missouri several years back , it is 6" long 2" across and real dense and hard
Yep, that's it. Good ID Jeff!
I know that I've got some specimens around here that I've also found in the midwest(Kansas). The sedimentary composition of the area yields many examples of your find and also crinoids, bivalves and brachiopods.