Description from the last photo in the album:
So... what is Chim Eater?
Given that it has no name in Rebirth, and definitely isn't used in Redemption, one can assume that this may have been the original enemy of the missing Chim Quest. Instead of the Assassin Dad kicking them all, apparently this shadow beast was to devour them instead. Either that was too gruesome, or the testers couldn't find the thing. It has no feet and it floats everywhere, so I doubt it kicked up a dust trail to follow. One could assume tracking Chim Eater down must have sucked horribly, since you only had a shadow to go by if anything, and if you only chased the shadow itself, you may have ended up in a position where you couldn't target it or something.
Whether I'm correct in my assumptions, I don't think we'll ever know for sure, but there you go.
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The original post:
It's my new avatar as well, because a floating shadow ball with big teeth sticking its tongue out looked cool.
Here's what I know: this creature, stuffed into 2tme and 2tme10 in the DATA.CVM files for all three games, is linked up in both Rebirth and Reminisce, but not in Redemption. The photos I took are from Redemption, and are proof that even if a model file isn't linked up, you can write in the file paths and pointers so long as you use space that isn't already taken up by another model's path data. I simply didn't care to try before now.
If you could see it without the shadow effect that makes it mostly see-through, it would look red-orange, like in the model skin:

Unfortunately, that's it. I don't remember ever seeing this thing before (it's not in the Moon Tree raid, like I mention in the photo album), and the model's construction may be off like with the Grunties since I used a generic PC to make it appear (see this link if you don't know what I'm talking about), but if this appeared in Rebirth somewhere, then it should be very quickly recognizable regardless to someone that cared about that glorified demo.
For now, I am merely assuming this is The World's Langolier, or perhaps a corrupt AIDA Chim Chim, given that skin kinda makes me think of a freaked out Assassin Dad that's stripped its clothing off and is high on crack.