I just started a new reef tank, all I got in the tank is live rock, 2 damsels and a bit of hair algae. I see some detritus on the bottom of the tank (no sand in the tank yet) and there are a bunch of small green cylindrical things about 1 mm in dia. and about 5 mm long with a slight curl to them, they look like plastic pellets but they crush easily and so they are soft. I don't think it is fish poop since there are too many and also damsels don't poop out pellets I think. They seem to be dead in that they don't move. What are they? Some sort of worm castings or?