A vivarium substrate has to do two jobs at once: hold enough moisture for a tropical animal and still let it dig, and most bagged substrates are either compressed too hard for burrowing or so loose they dry out in a day.

Komodo's Tropical Terrain brick is compressed rather than bagged loose, and it expands to seven times its size once it is placed in water, which is what makes a small, easy-to-store brick turn into enough substrate to fill a tank. It is intended for woodland and rainforest-style setups and is built to encourage natural burrowing behaviour once expanded.

• 10 x 20 x 6cm compressed brick
• Expands to 7 times its size in water
• For woodland or rainforest vivarium styles
• Encourages natural burrowing behaviour
• Chosen by professional breeders, per Komodo

On species. Komodo describe this as a tropical, humidity-loving substrate rather than an arid or desert one, so it is the wrong choice for a species that needs a dry setup — check what your reptile actually needs before you soak the brick.

Who it's for: keepers setting up or refreshing a humid, tropical vivarium who want a substrate that stores flat and expands on demand rather than a bulky bag that needs storage space.