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I just started watching Game of Thrones again and noticed something that I had never noticed previously. In the very first episode of the first series during the opening segment (just before the title sequence), there is a scene where one of the Rangers (in the books I think it is Gared) comes across a collection of the dismembered body parts from slaughtered Wildlings. The scene shifts to an aerial shot and it appears that those body parts are arranged in a crude circle with a line through the centre.
After noticing this it made me also recall that in a later episode there is a similar scene where severed horses heads and bodies are arranged in a pattern (I can't remember exactly but it was something like a spiral arrangement).
Are there any known reasons for White Walkers to arrange body parts in these geometric patterns? I certainly cannot recall anything mentioned in the TV series itself but I wonder if perhaps in any interviews with the TV show creators it is mentioned/explained? I thought it might simply be to create an additional sense of unease around the scenes and to perhaps enhance the sinister nature of the White Walkers but that is pure speculation on my part. I can't recall this behaviour mentioned anywhere within the books so the question applies just to the TV series.