I've been reading around to see if I could figure out what it is and most people that have had the same question answered it was a rectal prolapse but it doesn't seem to be that big. I don't know the size of a rectal prolapse but I feel like it would be bigger that what Nigel has hanging from him. It's very thin and light brown about a few centimeters long. Any ideas? I'm taking him to the vet for his arm. I've just noticed it today so he hasn't been like that for a while of anything.