Dust Bunnies

Small bunnies made of dust that start out as normal dustbunnies, just like our world, but if left alone long enough, it will gain magic and become a bunny. It will then start eating your food and pooping in places unless swept or vacuumed or catch and released (all three result in death), and they cannot easily be kept as pets because they rapidly reproduce by turning any dust it finds into dust bunnies. It often requires magical extermination to rid an infestation.