Dunno why, but a quick glance at that article made me go "oh, it's just wave interference" and all the "look at the weird geometric shape at the pole of this planet" things suddenly made perfect sense.

... I mean, that might not actually be the explanation, but that's the intuition those bucket-photos brought to mind.

[EDIT] Clearly the "just", above, is doing a lot of heavy lifting, but you stretch some waves into a circle and then squish them down (say, against a point, like a pole) and you're gonna get polygon-ish shapes, right? The particulars are probably complex, but the notion that you'd get "artificial"-looking shapes at poles seems natural, now.