I've had this specimen sitting in my "I'll get to it later" pile since last year. I've learned a lot about Cephalopods the past year, one of them being the differences between Nautiloids and Ammonoids.
Upon re-inspection of this yesterday, I noticed the shell lines, but more importantly the suture lines caught my eye. These do exist here, but I would call them pretty rare to find. Not being an expert, I would consider Wellerites or Schistoceras, but these are based on quick comparisons using a Pennsylvanian Cephalopods of Ohio book I have. I started to clean up the rock using an air scribe, but I've only got about 30 minutes into it so far.
I need to take much better photos, but the shell exterior is messy like this. You really need to rotate it under light and/or a microscope to see the sutures great.
There is so scale in the photo, but it's 20mm from front to back of the inner exposed whorl. The top of the photo is still more shell continuing on another 9mm and I started to expose more suture pattern there. The top of the exposed whorl has some shell material pattern shown in a black color.