Common in nature, good for a nesting box, but your taking a chance if used on an entire habitat. There has been more than one incident of intestinal inpaction due to sand substrate. One breeder lost a $5000 Lewisi to sand. Iggy was picking up a little at a time. Owner did not think anything of it until the deficatons stopped. By the time the vet got involved there were complications and it was too late.