Mixed views on Asterina Stars?

[CoralineCori]

I have had a few of these hitch-hikers show up from time to time in my tank and have heard they are harmless and beneficial in a reef tank. Also heard they are pests and will eat polyps on SPS corals and take over the tank if not pulled out by hand or with tweezers. So what IS the deal with these mysterious little things? Looking for some views from my fellow Canreefer's!