What am I holding

[sw33ts]

Found in central KY, I assume it's a shell but I'd like to know more

[sw33ts]

[Ludwigia]

Rugose coral.

[Tidgy's Dad]

Very pretty horn coral.

Nice specimen.

[FossilNerd]

I agree. Definitely a solitary rugose “horn” coral. There are a couple of different ones found in multiple formations here in Central Kentucky. 
 

The septa in the calyx (ridges in the cup shaped end) and epitheca (outer layer) look to be fairly worn so it’s hard to ID down to a genus or species . Lack of a more specific location doesn’t help either.

 

Still, I like your specimen. I’m a sucker for horn coral. 

 

https://en.m.wikipedia.org/wiki/Rugosa