Possible fossil ~ any ideas?

[RiverHunter312]

Hello everyone!

 

I hope the summer is treating everyone well. Here in Chicago it has been either great storms or brutal heat. I have had very little time or ability to get out but last week the weather evened out I got to do some exploring. I always head to areas where water has flooded and uncovered fresh places to look. Last week I found the item pictured below just siting on the surface. The shape caught my eye and it made me think of a nautilus-type shell. The ridges follow all around the surface of the "shell."

 

This was found on the DuPage river about 25 miles West of Chicago.

 

We are just in the edge of the Slurian area but just east of the Pennsylvanian region. When consulting online guides for Illinois, this looks like an incomplete endolobus shell.

 

Any ideas? Thank you for your time and help!

[ynot]

Piece of a nautiloid.

[Fossildude19]

I agree. This looks like some sort of nautiloid.

[RiverHunter312]

19 minutes ago, Fossildude19 said:

I agree. This looks like some sort of nautiloid.

Thank you for your response! I am very excited about this if it is. 

[RiverHunter312]

24 minutes ago, ynot said:

Piece of a nautiloid.

Thank you for your reply! I appreciate it!