When they attack/move it appears they curl in (the side squeeze in to get the legs under them), this makes them a little taller, shorter and narrower and makes them seem like they got smaller because the narrowing is greater than the extra height. But if you spend some time and look at them pretty closely that is what is going on as best I can tell.
And here I thought you were going to talk about the unbreakable eggs (I still run into them, have to leave the area and come back before it can be damaged and yes, I and others in the game have all taken turns trying to pound on them, from both sides in the case were you can get to the other side via another route), and the bugs that will burrow and never come back up so you can't walk through that area, that one doesn't always get fixed by going back to town or another Act either.
Edit: Had to fix a few typos.
And here I thought you were going to talk about the unbreakable eggs (I still run into them, have to leave the area and come back before it can be damaged and yes, I and others in the game have all taken turns trying to pound on them, from both sides in the case were you can get to the other side via another route), and the bugs that will burrow and never come back up so you can't walk through that area, that one doesn't always get fixed by going back to town or another Act either.
Edit: Had to fix a few typos.
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It's all just zeroes and ones and duct tape in the end.
It's all just zeroes and ones and duct tape in the end.