Please help me ID this (South-Western Indiana)

[cmsmith9]

This is my first post here. I’m not sure what I have here. Possibly fossil coral or some form of metamorphic rock.
 

I live in south-western Indiana, Sullivan County specifically. It is my understanding that most rocks here date from the late Pennsylvanian. Terrestrial plant fossils seem to be most common here but these vaguely resemble coral. I’ve never seen rock like this before and would greatly appreciate if someone can help me ID this.

 

Thanks guys.

[Ludwigia]

Looks vulcanic. Might even be slag.

[cmsmith9]

It’s slag. You’re absolutely correct. I had no idea what slag even was until a minute ago but a Google Image search confirmed it. What a drag, I thought it might be something interesting but, as usual, it wasn’t.

 

Thanks Ludwiga.