Sorry I didn't get to reply, I got sick pretty bad.
It is just a random growth. Thanks for the tips! The game was supposed to be a simple factory building rogue-lite where you keep the gold you mine to upgrade your structures, scale the map and so on. I watched two Brackeys videos on Godot during the first day of the jam and then I felt a bit too confident. I finished the tile layer and ore system after a lot of docs and struggle and then realized that there is no way I am finishing this. Thanks a lot, loved your game btw!