Honestly, life evolves in different ways, but the form of xenia polyps and their feathery apendages remind me of 2 methods which are used for survival in marine animals.
1) The Gill, yes the freakin gill, of course... used to exrtract oxygen from the water column. If xenia use their feathery appendages like gills, they may be extracting such essential elements from the water column simply by pulsing water through its feathery gill-like appendages to extract amino acids, nitrigen particles, other trace elements, maybe iodine, etc... some biologist can figure it out.
2) Like tube worms, but without a method to feed, allow esstial elements to cross aborbsion areas where it can use new, fresh, water to cross such critical areas for such food/minerals/elements to be absorbed.
Last but not least, i have noticed that xenia like to pulse when there is little to no water flow. When the water is turbulent, why use your feathery like apendages to push water through when a power head is doing it for you? now without a strong current, its time to manually apply such a method for causing water to push through to get those vital elements/amino acids/other stuff you need to survive. Maybe they pulse more in the ocean during slack tides and less turbulent conditions. Another reason for them not pulsing may be they are lacking the essential minereals, food, nutrients, etc to produce the energy to pulse. If so, many have suggested the addition of iodine, trace elements, magnesium, fresh water change, whatever else helps you can apply here... Also many people have used the xenia as a water change indicator. When they stopped pulsing, people would give water changes and notice the xenia pulsing away again... until the next water change is needed. I feel this is why they pulse in the first place, and how they can stop pulsing, and applied to the proper conditions the right methods can be applied to get your xenia pulsing again.
