AT a pet store I used to work at, they got a litter of patchwork or double rex rats. They were really cool. They would grow a fuzzy layer of unevern fur, then lose it, then grow it back. This would go on for some time until they reached maturity, then they ended up however (some had all peach fuzz, some had tufts here and there, and some were completely hairless) I thought they were pretty cool and bought one for my friend who lost his pet rat. MOst people thought they were ugly.