Actually, what I have is a close look at some seeds that people (some of us) eat. Brown flax seeds are pretty small compared to, say, pumpkin seeds. But chia seeds are a lot smaller. To the eye, if you don't have the "advantage" of myopia (I was never nearsighted, and now I deal with presbyopia), they look almost black like poppy seeds. Under magnification and strong cross-lighting they show quite a lot of tonal variation. Flax on the bottom, chia on top:
Looks a little like pebbles on the beach, and maybe tiny shells. Interesting textures, at any rate. Sometimes it's fun to take a closer look at things that we see every day.