I have several concentratons of these brown splotches. Each one is not as wide as a pencil eraser, there are smaller and larger versions of these. I assumed they were algae but after looking closer I think they maybe a creature as they appear to have a head, although I have never seen them move. Anybody got any ideas? They definitely are not on any of the corals or zoo's, only on the rocks or sand. I only find them in concentrations which are fairly bare of algae/cyano, not sure if that is a result of them being there. They are not causing any harm but was hoping to find out what they are if someone knew.