No, but they're going to fall over and the bottoms of the coral will die, possibly causing RTN, but it's all about how well your tank is to supporting SPS. I bought plugs, but don't use them for corals that I recieve from other people, only frags that I make for other people. I dont' want my tank full of plugged corals. And even then, they end up growing over the plugs, which I've seen a few times in my tank already, where I had them attached to the rock at the plug, but the coral overgrew the plug.