No, the actual ground/mountains.
Was quite awhile ago now but I recall Red saying (in JAVA) that lower tier ore veins would regrow after a time which would mean the surrounding earth as well.
I never worked on a project long enough to confirm or deny but some voice in my head took that to mean the earth with no ore would also regrow/heal eventually, though Im thinking it through as I write this and realizing Im likely mistaken.
Anyway, I started an intensive terraform project in Unity and had a fear it would eventually wreck itself. *shrugs
thats the first time i hear this. but there was a bug in java that allowed you to "regrow" veins when you manually fill them with rock again. that wasn´t on purpose though