image

I guess, this is a isolated siphuncle of a discosorid (nautiloidea).

@Pumpkinhead This is a dead ringer for Stokesoceras sp. cf. S. engadinense Foerste. There is an equivalent one in the Thornloe Fm. Nice find! (Yes, very late to the party here. ). 

For comparison, image from

Bolton, T.E., Copeland, M.J. (1972). Paleozoic Formations and Silurian Biostratigraphy, Lake Timiskaming Region, Ontario and Quebec. Geological Survey of Canada Special Papers 72-15: 1-49.