It originally took about six weeks for it to attach to the LR so your warning is well taken Bob. I think what I am going to do is leave it in place and just monitor the spread of the "dry rot". My choices are either to disturb a lot of my LR to get the rock out so that I can frag it out of the tank, frag it in place (bit wary of that as well given that the general consensus in a lot of the stuff that I have read advises against this - and I am still not convinced about Vipers' brute force method!), or leave it be and watch. Nothing else in my system seems to be worried about/affected by the "dry rot" so I guess I am going to take the easy route!