Hoping this is from a trilobite?

[Brishen1]

After taking @caldigger's advice I went back to this gravel dump in Indianapolis. I found a few more pieces of Horn Coral, but this guy was a mystery. I'm hoping its part of a trilobite and not coprolite. 

 

Thanks in advance!

Edited July 23, 2019 by Brishen1
Misspelling

[Kane]

Almost as good: I would say orthocone nautiloid.

[FossilDAWG]

I concur, orthoconic (straight-shelled) nautiloid.

 

Don

[Brishen1]

Awesome! Thanks @Kane @FossilDAWG