I love the idea of rock, water, tree. I will teach it to my 3-year old, who's only now getting the hang of rock, paper, scissors. I do think the directionality of what conquers what is really not that obvious, though, because it depends on so many factors. In the image at the top, you said: "Tree and Rock caught in an ongoing struggle. Though the eventual victor is clear." I honestly can't tell without a time-lapse which one is going to win.

When I was younger, my father asked me what's stronger: concrete or plants. In the short run, he said, newly poured concrete can impede a plant's growth, but in the long run, plants can find their way up through the cracks. It's a never-ending dance, as long as we can stop making so much concrete at some point.