Ok, we don't know if Thargs have something to do with the UA or not. It could be not Alien at all, or hybrid in some way, as pointed elsewhere (even if it really seems Alien to me, really, Alien and organic).
Someone somewhere said that a Developer pointed that Thargs use an octal system, because they have 8 fingers.
Can we take it in account while testing?
Is there a source for this "Thargoids use octal/have 8 fingers" idea? Because Drew Wagar wrote a good summary of the lore at http://www.drewwagar.com/progress-report/thargoids-the-definitive-guide/, and he doesn't mention that.
I think a lot of the connection between Thargoids and the number 8 is simply down to the the motherships having 8 sides. But Thargons, the drone attack ships, were not octagonal. Thargoids may have 8 limbs (according to one of the official novels), but we have 4 limbs and yet base-4 seems to be pretty rare among human societies.
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Aye maybe it is actually a space station for a tiny race of beings?
"What is this? A space station for ants?"