I've had many pets during my life. In all periods it had always been more than one animal, so it's hard to choose only one to describe. There's one pet that no one ever seen, though.
It is a cat. It has no name as I don't know where she comes from. It has no a bowl to eat from. It's just here. It's a girl. She sometimes passes my bed touching me with her gentle tail. She seldom shows up. She has bright white long fur and blue eyes. She's quite soft and she is not playful. She usually comes, watches me and disappears.
You can call her whatever you want a ghost, a creature from the alternative reality or just my imagination, because you won't see her as no one sees.
I can't explain her presence in my house either. I just believe that she comes with good intentions.