The Factorio\data\space-age\graphics\entity\stomper folder contains 70MB of unused textures from old Stomper versions.
[GFX] [2.0.21] 70MB of unused old stomper-corpse textures
Re: [2.0.21] 70MB of unused old stomper-corpse textures
I forwarded this onto GFX. From what I can tell, they're suppose to be used but the Lua definition is broken.
If you want to get ahold of me I'm almost always on Discord.