Yup, same question, do they move?
If they do move, they may be baby snails, pods, some other normal little critters, or could even be flatworms.
If they don't move, then featherdusters are likely. Feather dusters will look like a little coiled shell, and if you look closely a little fan like thing will come out but retract quickly if distrubed. Could also just be coralline algae starting.
Try to really look at them and describe in the most detail you can.