looks can be deceiving!
I spent a lot of time outside the tank stacking and shaping rocks. All the base rocks are to the bottom of tank, the big piece on the 2 black rocks wouldn't wobble with me pushing on it. The same for all the other structures, there is little to no wobble when pushed on. I do plan on watching it closely for any movement or shifting also once i stock it. Oh also a few of the pieces on the ends are just sitting there for now and will most likely end up somewhere else.