Hard to say for sure from the pic, but this one looks like it could have vermetid snails on the right and lower, right side of the plug:
I would inspect it close and see if those little tubes are hollow, with a "curly-q" on the bottom. If so, snap them off and scrape the area they were affixed very well.
A lot of tanks have them and they never really cause a problem, but I tore my 450 down after I went from a few to a few hundred thousand in a month! They send out little webs, which can irritate the polyps of SPS and other corals, keeping them from opening up and subsequently receeding.
Otherwise, that a nice patch of corals you got
