If you visit Falls of the Ohio State Park more than likely you will go under the Illinois Central 14th Street Railroad Bridge connecting Clarksville, Indiana and Louisville, Kentucky. The bridge was built in 1868 and crosses the Ohio River.
Some of the stones that support the bridge have fossils or mineral desposits in them and here is one I took a picture of. Unfortunately, I had the camera set for tungsten lighting while in bright sunlight so it made the image turn blue. I think this is some sort of coral but it has a white snow look to it like it is covered in salt.
I thought this was a coral fossil but after consulting the naturalist as that Falls of the Ohio State Park he told me it was calcium carbonate (travertine).
The bridge is also known as the Pennsylvania Railroad Bridge or Conrail Railroad Bridge.