Not that I would recommend it but did you touch them? Just asking because urchins do have tentacles that they put out, they are much more noticeable when their small....and that's a good question, are they moving around?
Okay, this is so weird. I figured out what they are. I got up the nerve to touch them with something and it pulled the polyps in and it's an SPS frag. They are little pieces off of my SPS frag above it. But they haven't been broken off. It's almost like it just sprouted babies and fell down.
Pocillopora are notorious for "polyp bailout," in which some, or all, of the polyps will bailout from the skeleton. Since the polyps are heavier than a lot of other SPS, they're more likely to survive all of our power heads and filtration, settling somewhere, to start a new colony.