I attached an anubia plant (which one, embarassingly, I don't know...) to a porous rock and then dismantled the tank about 2 months later. When I took the anubia out it had secured itself pretty well to the rock, and I had to pull at it quite a lot to get it to let go.
From my experience, (and now I think about it, it's pretty damn obvious), they seem to attach much better to things with lots of holes.