I've been testing a bunch of random things lately and one thing I just stumbled upon is that if you hide behind certain doodads you have a 100% invulnerability to spider mine damage. When I tested this I set the units to 1 HP and the mines to 999 DMG just to be sure. Some of these doodads invulnerability area is even much bigger than the size of the doodad. What's up with this? Is this a known thing? I first noticed it hiding behind the giant dome made up of triangles on the space tileset. I tested the majority of jungle tileset doodads and these are the ones that I have found to give invulnerability to mines.
From a quick test it seems that the doodads that give spidermine invulnerability do NOT give the normal ~46% miss chance that most other doodads give.