Cephalopod v. Calamite

While working for the USGS a few years ago, I found this fossil in Goose Creek out U.S. 42 near Prospect, KY. I am not positive what it is, but my best conclusion is that it is a Calamite stalk. It is about the right size for a younger trunk (4-6 cm across) and is segmented just like the description says. It is also very common in the Devonian Limestone which borders the Cincinnati arch. Long, segmented tubes could also be the shells of cephalopods, however, this is more plant like. It does have rounded ends like a cephalopod, but that may just be from the erosion of the creek. If anyone is a fossil junkie and can let me know, I'd appreciate it.