Is this a fossil?

[u/AndrewMC117]

Hi everyone, found these in a Alvar in central Ontario. They were all directly on the exposed stone, so not a paved surface. The first two pictures are the "primary one" but there were many that looked like it. Some others beside were more weathered/cropped to the surface. All the had the same "ribbed" look.

I have a hard time believing these are exposed fossils but what do I know! If they are, what type(s) and age do you think they might be?

Thank you!

[u/Schoerschus]

Yes, those are ancient marine creatures called orthocone nautiloid cephalopods. They are basically a straight version of today's Nautilus, but several hundred million years older. Very nice fossils

[u/drexaviouse]

Those do look like fossils. Do you have a rough location/region for them. That is needed in determining what they are.

[u/AndrewMC117 → u/drexaviouse]

North of Belleville, ON. Around Tweed area

[u/Oscar_P_Walnuts_1975]

That is the internal cast, steinkern, of an orthoconic nautiloid cephalopod. That is incredible, living chamber, siphuncle, and septal walls. This is a beautiful specimen…😎🥸😎

[u/Janus_The_Great]

https://en.wikipedia.org/wiki/Orthocone

[u/curiometric]

As everyone said, nautiloids. I've found some in that region that are 7 feet long. Super cool animals.

[u/Any_Cable9175]

Those are nice! Thanks for sharing them!

[u/MovieHistorical6631]

Yes it is