I've found these tiny, pale rice-shaped beasties on a few of my plants recently - an anthurium cutting and a couple philodendrons. The philos have sunken areas on some of their leaves that look like something's going around sucking out fluid from them, and I haven't seen strong indications of other pests that could be doing this.

I think the critters are insects, not a type of mite (I am more familiar with spider mites than I like), but they are so small, even with a 20x lens I'm not sure if I'm seeing 6 legs or more and I can't hold my phone steady enough to get an unblurry image. I've looked up a bunch of plant pest info but have not found anything like a good match for them, or whether these things are in a larval stage, or some are adults. The biggest ones are maybe a millimeter long, but I've found others much tinier.

They seem to prefer the upper surface of leaves. They move fairly quickly when they want to, but don't seem to have the best grip on the plants - I watched one fall off a nearly vertical leaf surface. For now, I've rinsed the plants off with the sink sprayer, because if they fall off all on their own, the water ought to dislodge them pretty well.

Any ideas what they are?