A reader of this blog, Christina sent me a image of fossil she found in Harrison County, Indiana, USA. I think it is a
Syringopora sp. coral fossil. All the fossils I have seen from Harrison County date to the Mississippian Period.
It is quite a nice find, especially if more fossil detail can be seen once the matrix has been removed.
UPDATE: Mike Huggins in the comments section left a link to a similar fossil he found. It is a "Upper Mississippian
Syringopora in limestone of the (Meramecian/Visean) Hillsdale Limestone of southern West Virginia"
https://www.flickr.com/photos/79475348@N03/14012502204/in/album-72157644301124792/