We have three chinchillas in one big cage. The other night their running wheel had fallen off inside the cage. What I didn't know was they were very frustrated with the situation. They were making so much noise I couldn't sleep so I reached in and took the wheels out. I tried to go back to sleep but things just got louder. I guess they were mad at me for taking the wheel out so I got back up put the wheel back in as it was suppose to go and they quiet down. How funny.