Multiple 2D Textures spawned

I’m having a problem with a lot of 2D textures being spawned in my level folder. I’m pretty sure they are related to my landscape but I’m not sure what they do.
Here is what they look like:

I’ve never noticed them before and they reappear if I delete them or move them. Can someone tell me what are they doing or how to get rid of them if they are not doing anything ?

Thank you for your time !