Some people have a similar reaction to porus/holey objects like http://farm2.static.flickr.com/1406/1093460880_2af2500cc8.jp... . It seems common enough that there's probably some instinctive reason for it. The image of the triangle has a kind of similar feel to it.
Wow that actually causes a mild fear reaction. It's like seeing something with many eyes and historically many-eyed creatures haven't been particularly friendly.
