There were also the burning rings of fire...
Subtrend: Flat and Circular
There's another, related type of dystopian cover images that I think of as the manhole covers -- I'm a city person -- but maybe you'd say they were inspired by gears or a horoscope vector or a clockface:
Tell me what you think about cover lookalikes: do similar covers create a sense of association in your mind? And if so, is it a positive association, or an "no, not that again" feeling?