Thanks! It's fairly simple: driftwood, cork, Great Stuff foam (the yellow to give depth), acrylic paint (hide the Great Stuff), filter, pump, tubing, fern, two kinds of ivy, four kinds of moss, a touch of slate, super glue gel (attach the cork to the glass or you can use aquarium sealant, also a touch here and there to attack moss to wall).
The art is just putting that all together. ;)