Moke

The Moke is a lizard with silver-green skin that is native to the British Isles. It can reach up to ten inches in length. The Moke has never been noticed by Muggles since it has the ability to shrink at will.

Mokeskin is highly prized in the making of purses and money-bags. A Mokeskin purse will shrink at the approach of a stranger, making it virtually impossible for a stranger to find. Once the owner puts something inside the bag, no one but the owner can get it out. Rubeus Hagrid gave Harry Potter a Mokeskin bag as a gift on his seventeenth birthday.

Appearances

 * Fantastic Beasts and Where to Find Them 
 * Harry Potter and the Deathly Hallows