Just an assortment of artificial plants from PetSmart. They do love that fern. They get in it. They like to watch the shadows of the crickets that walk on it (and jump).
I have mostly floating platforms, so I am very limited in weight, or the platform sinks.
Also one of those hollow resin bog logs.
Since I have 7" of water, I need to adjust height of solid non-floating objects.
For adjusting height, I ordered a set of acrylic display stands, 3", 4" and 5". The bog log sits on the 4" stand and I expect to add a corner waterfall feature that will sit on a 5" stand.
So far, these frogs have explored every inch of whatever I put in that tank.