Fern spores wiggle around like insects

If I didn't know these were fern spores, I'd think I was looking at a mountain of squirming insects. It's freaky and mesmerizing to watch! The video embedded below explains why the spores behave this way.

"Look at the underside of a fern leaf. Those rows of orange clusters aren't tiny insects; they're spores waiting to be catapulted away. Once a spore lands, it grows into a tiny plant, from which fern sperm swim away, searching for an egg to fertilize. Think of that next time you're hiking in the forest."

See Also: Gorgeous footage of mushrooms wisping spores