im not sure of the name of it, but it came as 3 pieces, i didnt have to cut anything or use any type of silicone or glue at all, the bouyancy of the background keeps it in place, and i installed it while doing a water change it was very simple. and no it doesnt ever come loose, i dont think it ever would either its pretty tight, the bouyancy makes it tight to the lip of the tank and the substrate holds the bottom in place, no worries!
driftwood your ornatus looks nice! when did his pearls start to show? mine are juuuust barely visable now. their aggression is mild, if you watch the whole video you'll see them nip and chase eachother away, but i have yet to see how they do as young adults