Digging is a core rat behaviour, and a dig box is probably the highest-value enrichment per pound you will ever provide. The box: any wide, shallow-sided storage tub, litter tray or under-bed box that fits in the cage or the play area. Deeper is better - 10 to 20 cm of fill. Safe fills: coco coir (soaked and squeezed out), children's play sand (washed, not builder's sand), soil that is pesticide- and fertiliser-free, kiln-dried aspen, shredded paper, dried leaves, or a ball pit of plastic balls. Sprout wheatgrass or oats in soil for a living dig box. Avoid: dusty sand, chinchilla dust bath (respiratory irritation), scented soils, compost with additives or fungus, and anything mouldy. Make it a foraging box too: bury peas, dried mealworms, bits of pasta, or scatter the dry mix through it. Practicalities: it will get everywhere. Site it in the base of the cage with a lip, or run it as a play-time-only box on a towel or a plastic sheet. Sieve or replace weekly, sooner if it is being used as a toilet. If your Cage Score in the Dream Cage keeps telling you your mischief wants somewhere to dig, this is why.