I've got a large mammal, basically a nutria, living in my couch. Maybe grandma had the couch before, and she pointed it out to me. You never see the animal because he is nocturnal, and I've had him living there quite a while without ever noticing. But if you wake him up in the daytime, he will come out.

I wake him up by pounding and making loud noises. Bending down to peek through a slot in the couch (which is big, like a foldout bed) I can see him peeking out. He seems quite intelligent and aware. Eventually he comes out and roams the house. I pet him, but his fur is kind of greasy and not very pleasant to the touch.

He seems rather large to be living in the couch, and I'm sure that a mess is developing somewhere, but I'm not sure what to do.