I had these for awhile. Also seen similar things called seed shrimp.
I added a couple of psuedomugil red neon rainbow fish, and they ate them. I think they probably ate some of my pumpkin shrimp babies as well if I had to guess, but that wasn't really a problem as I still constantly have babies.
I lost both rainbow fish (jumpers) over a few months, but I haven't seen the seed shrimp return.
So I think some fish will eat them over time if they bother you. They did seem to be harmless as mentioned, but they always kind of annoyed me.