I just found these new creatures on a few of my frag plugs. I am searching my acros and don't see anything yet. I've never seen them before. I did pick up a bunch of frags at the swap and did not QT.
From the look of it, those aren't the bad type. While they are photosynthetic FWs... and can become a PITA... those aren't the types that cover corals. Those guys you will find eventually on your glass. Not so easy to eradicate in larger tanks.
Purchase some FW Exit and dose your tank, these are some of the reasons for dipping corals prior to adding into your tank.