Many people consider the choice of substrate to be simply aesthetic. However, the substrate has a greater effect than just decoration, and provides a microclimate environment that can affect the health of the inhabitants. Although choosing the substrate is partially a matter of the owner's personal preferences, it must also take into account the needs of the occupants. Burrowing species for example will prefer both a depth of substrate and a type that they can easily tunnel through. It might be important to have a very dry, easy to clean bedding such as CaCO3 Sand for a desert species. Some amphibians and reptiles will require a more humid substrate like Tropical Terrain to simulate rain forest conditions. In many habitats the ideal solution may be to provide a selection of diverse substrates at different levels. This will provide a variety of environments as well as a more natural and visually attractive living space.