
Snow fleas. Tiny insects of the springtail family, millions of them, on one of their warm-winter-day frolics. Put your hand down near them and they hop all over you. Lift you hand away from the ground and they abandon ship.
To the eye, featureless specks. I gathered some into an envelope and took them to the biology lab to have a look through a stereo microscope. Of course, they wouldn't sit still. I moistened the glue on the envelope's flap and a few snow fleas got stuck in place, wiggling furiously -- legs, antennae, segmented bodies, and the spring-loaded tails that flip them through the air.
Almost invisibly small, but assembled by their genes, atom by atom -- eyes, mouth, belly, anus, genitals, heart, brain, nervous system -- something like 10 quadrillion atoms in all (by my rough calculation), every one in its proper place.