Hay, sticks, poo, and pellets. All of them all over the cage, all over the floor around the cage. The sticks especially. Each night they get 2 new sticks and 2 old sticks and every morning there are 4 sticks strategically thrown in front of my bedroom door for me to step on and put back in the cage. Hay holders are useless, they just pull the hay out of the holders and pick through it tossing anything not up to their standards. Half eaten pellets (and poo) get thrown out of the cage when they are done most of the time, and the dish is knocked over about twice a week. Their newest is the lava ledge, one chews on it while the other rolls around in the hammock below that is catching all the crumbs and dust, which in turn gets is all over the floor. I find poo and hay all over the house, in rooms they aren't allowed in and have never been in. I only have 2, I couldn't imagine the mess from a barn-full!