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I have just started some green star polyps in a non-octo tank and have noticed that they are VERY sensitive to being touched. I suspect the octo will be fine with them but I am not sure how well the corals will do with the octo interaction.
I had a reef tank for ~10 years before I decided to change to octo. GSP is almost like nuisance coral or a weed once it gets going. It is all I have in my tank right now (long story). Last night I saw my octo glide across the GSP on the back wall and even stop on it.
It will be interesting to see how the green poly star reacts. I put it and some xenia in my otherwise empty tank in hopes that it would cover most of the rock-work, then I will add a fish and maybe a couple of inverts.