Xenia. Some reefkeepers hate it because it grows and spreads so prolifically. Others love it because of its constant motion and unique appearance.
The Xenia lovers have a point. This coral doesnt just sway in the breeze – each of the feathery polyps actively opens and closes in a hypnotizing rhythm. Even though its not fluorescent at all, and doesnt glow under the blue lights, it is absolutely eye-catching.
But the Xeniaphobes have a point too — this coral grows fast and likes to spread. If you want to keep it under control, I suggest confining it to a rock island of its own, and pruning it (outside of the tank) if the colony gets too large. Or, just embrace the Xenia and let it spread!
The frag you purchase will come from the same lineage as the image shown, and will have a similar number of polyps, but because of natural variation among frags yours may not look identical to this image.