Buffalo Gap Grasslands - South Dakota - ID

[DakotaBirder]

My son and I have recently started visiting the Buffalo Gap National Grasslands to hunt for agates and other goodies. Today we came across something that we haven't found. About an inch and a half long, vertical structures that come together at center points on each end.  Found in an area with plenty of petrified wood.

[jpc]

This looks like a very worn horn coral or somesuch.  Probably washed in from the Black Hills as it is likely too old to be from any of the rocks on the Grasslands.  The National Grassland has late Cretaceous to Oligocene rocks and these things (if it is a horn coral) are Paleozoic.  

[fossilized6s]

Looks like a typical horn coral to me. And JP is right. Too old for the grasslands. Cool thing is, it got there some how! 

[Miocene_Mason]

+1 for horn coral, which did in fact go extinct in the Permian extinction

[Rockwood]

9 hours ago, jpc said:

 Probably washed in from the Black Hills

Keep in mind that they were body surfing the Black Hills as they washed away from themselves.