The Problem
select the normals & recalculate outside
The result
Please help
I’m assuming the object is made from multiple pieces? If yes, you can hover your cursor over a piece and press “L” to select it. Then, try recalculating or flipping the normals just for that one piece.
Also, it’s hard to tell from a small picture, but it looks like the polygons are pretty messy. If you have modeling problems like overlapping geometry, interior faces or edges attached to 3 faces, that can make recalculating normals go wrong.
You could use a remesh modifier on the rocks and apply it. That would almost certainly correct the issue.
I’ll give both of those a shot. This is a very very tiny piece of a castle from HP that was made by someone and free to download, I then took the whole model and squished it, so my buddy could have the whole castle on top of his monitor LOL. Was hoping something more automatic