I couldn't think of a better title because I'm not sure what's going on with this phenomenon--someone who has an answer, please edit to fit this better.
I noticed that when I cook rice, at some point after most of the water has evaporated and the rice is settled at the bottom of the pot, there is a "lattice" of regularly-spaced gaps in how the grains at the top are arranged, with the holes extending down a grain or two.
I can try to explain this better if it doesn't make sense, but for now I can't do much better because it mystifies me. What's up here?
(Better tag suggestions are also welcome...)