I have the exact same issue right now. Mine are almost square,4mm, and are growing in #'s rapidly. There must be close to a 1000 of them. They don't seem to be causing any harm. I have many many unique critters in my reef, and none of them cause any harm to corals. Just wondering about these??? I can't get pics of mine either.....too small.
Let's get this figured out.
Thanks for the thread.
I will keep you posted, you please do the same.