Well, they do seem to understand and stay away. I have seen one of my dragonface bump into a torch tentacle and jerk away very suddenly. But it seemed unharmed. I'm sure a couple wrong moves and one could end up dead from being stung. But it seems a relatively low risk and within the parameters of my "live and let live" philosophy for my reef. I have quite a bit of open sand bed. If I had a tank jam packed with nems, I could see that being a big problem. The pipes are unfazed by shrooms, zoas, leathers, etc. They'll sit right on them.