Desert substrate. 2.27k. Fine.

Desert Substrate™, an easily managed alternative
to sand and gravel. Where sand and gravel are used
in dry situations, Desert Substrate is a lighter,
cleaner alternative. It is made from heat treated
corn cob kernels and so it is biodegradable and
ecologically friendly. Being totally organic, it
poses few, if any, risks to the animals it is used
with, the humans who use it or the environment.
Like all the "Advanced Vivarium Substrates",
Desert Substrate combines the performance of applied
technology with the responsibility of sustainable usage.