Scatter them across any substrate to add a naturalistic element to your vivarium design... but even better they are amazing in bioactive set ups. Not only do they provide hides and cover for many species, but they will also decompose for your clean up crew and add extra nutrients into the soil for your plants. Inverts such as millipedes and isopods will benefit hugely from the addition of these kinds of leaves to their enclosures as they will add an extra natural food source once they start to break down.
These are a natural product and therefore may differ from the image.