It's on a plug, was a tiny piece when purchased about a month ago, and has at least quadrupled in size. It's starting to overrun the plug as you can see, was waiting until I added some more rock that is currently brewing to make a decision. I have everything temporarily on a shelf rock while I wait and decide. I was thinking about buying a magnet frag holder and placing it on the back glass, kind of like that look. Also was thinking of cutting and making more at some point and use on places where rock meets sand (like grass). It is probably in my top 5 favorites but maybe I'm biased as I run a lawn/landscape company
My CUC doesn't consist of anything that wants to feed upon shelf rock other than the lawnmower blenny. Even then, it doesn't look like it goes anywhere near the GSP for whatever reason. The other fish swim around up there but never stop to graze, probably because all of them get full on nori.