Alpena, Michigan oddities from Potter Farm formation

[Cassandra Tiensivu]

Here’s one (technically three) from the Potter Farm formation (Alpena, MI) that I really have no idea on. Crinoid, maybe? All three pieces are basically the same. I just set them up at different angles so you could see how they looked from different views. 
 

Any thoughts?

 

[TqB]

I think they're crinoid arm ossicles, showing the ambulacral groove (food transportation groove).

It's surprisingly difficult to find a good image but this gives the idea, from:

https://people.uwec.edu/jolhm/cave2005/group4/Crinoidea.htm

 

 

A couple of arms from the same species which I don't know (Mississippian, Brigantian Stage northern England), the first one showing the groove though the left hand side needs prepping out.

Edited September 14, 2022 by TqB