I have seen them refered to as Pale blue palys, and I agree they are a nuisance type of coral.
They multiply rapidly and can quickly over take your LR.
lol mix some calc in hot water into a thick paste and stop the flow in the tank and slowly cover them all ..
the paste should be thick and then they get covered and die eventually and white paste would be turned to rock color or pick based on your coraline algae
DONOT try pulling them off and they spread mor rapidly and if they are protopalys they might sting you also