Here's my Tonga rock structure on the left side of the tank. Its view was blocked by the piece of rock next to the toadstool, otherwise you can see more of the base. What I did what I drilled holes on pieces of flat rock, then stuck the branches in and glued them with Aquamend. It was time consuming because I used the $3/set of hole-saw blades from Harbor Freight, and drilling through rock is not easy
. But I'm very happy with the results and all the feedbacks I got from people who saw my aquascape.
Here's another picture of the scape without that piece of rock blocking the view .. not much different though. The flat rocks bases were buried under the sand to make it look like the coral trees just grew from sand
. It's a waste putting them in your sump