The ventral surface of Asterella can iridesce

 

Who knew? 

Here is its dorsum by the way (I assume the yellow crumbs are pollen from some bush or someth- edit: wait a minute, just realized the thing has macroscopic spores! These are probably what they look like, I shook a sporophyte repeatedly and they kept falling out.)

Followup to below

I've been seeing large aggregations of various synanthropic native and invasive aphidophages (golly gee, what a lot of adjectives) in the wilderness, but only near weedy mustard megaclusters. Presumably they are murdering various mustard aphids.

More "pristine" habitat remains low in insect density, with a few exceptions.