They are known as a Familiar.
Witches do not exist and hence i cannot think of any animal which would do so.
a mouse
The witches hat is at Graices or Able sisters. Check.
Occasionally, your Animal Friend will give you things, and Animal Friend clothing is one of them.
Familiar
the animal known to be mans best friend is a dog
he discovered them by checking if they were old owned and animal and if they lived alone
Tartar is not an animal your friend Lianah
if the animal is worthey to him
Witches do not perform experiments. They perform spells and rituals similar to what other religions perform. As far as the correlation between cats and witches goes. Most Witches (or Wiccans or member of any other Pagan sect) are worshipers of nature. Most witches have what is called a Familiar. A familiar is an animal that a person chooses as their pet. Sometimes they are considered their spirit animal. Not all "Witches" are cat people. Some like other animals like dogs or really any other animal that is tame and could be considered a pet. Cats are an extremely mysterious creature. Cat's already have a lot of superstitious ideas laid upon them so when you add that to the reputations of Witches or the Occult arts you basically get a heavy and very mysterious vibe to Pagan practitioners.
A diamond friend on Pixie Hollow is simply either A) an Animal friend that has been upgraded with diamonds, or B) an Animal friend that was bought with diamonds
friend