Time and again the vegetation was removed, and then, before new vegetation maybe took its place, a pattern of rough semicircles was revealed on the wall, often layered on top of each other, light patches scratched and etched in the concrete by all the bunches, fans, and trailing streamers as they brushed back and forth. If that stretch of wild growth had earlier appeared random, when it was cleared away the half-ring or half-moon forms left behind in its absence appeared entirely orderly. They differed only in size, and were rounded off either at the top or the bottom, depending on whether the plants had been growing up from below or hanging down from above.