I got my first pulsing xenia last week and have been watching it extend and wave around for a while and then tighten up into a small little ball. I was not sure why this happened, maybe just getting used to a new environment. Today I noticed that the xenia looked damaged like something was picking at it. Well sure enough a couple hours later I saw my big emeral crab (boris) picking at it. I thought emerald crabs were reef safe. By the way, Boris is now in Quarantine wating for his trip to the fish store.