Thank you all for the replies. I am very happy it's not Aiptasia! Think they may be a featherduster? I can kind of see how they resemble the vermetid snails you posted. They seem to be spreading and popping up all about. We feed the tank a small amount of cyclop-eze and you can see they are translucent and then turn red as they grab and eat the cyclop-eze from the water column.