Aquascaping With Branch Type Live Rock

[Palster]

I am in the process of curing some Tonga Deepwater live rock. This rock has a narrow bottom and branches out at the top. The rock is going into a tall 20 gallon Hexagon shaped tank and I was hoping to be able to make the rock stand up with the narrow end of the live rock at the bottom of the tank. Does anybody have any suggestions on how to secure this rock so that it will stand up (kind of like a tree) without falling over? Because this is a tall and narrow tank I want the rock to stand up as I believe this will look the best, but it will definitely not stand up unless I secure it in some manner. I do not want to lean the rock against the back of the tank as the tank is acrylic and will scratch. I have 3 pieces of live rock to secure in total (one large piece and 2 smaller pieces).