Pogrebin

Pogrebins are a fictional species mentioned in the Harry Potter series.

Description
Pogrebins are one-foot-tall creatures native to Russia. It is able to crouch itself down to resemble an ordinary pile of rocks, allowing him to tail a human being and immediately hide when the human turns round. After seeing the same rock several time, the human will eventually crouch down to examin it more closely, and the Pogrebin will then try to take advantage of this to devour the human. However, if one has fast enough reflexes, the Pogrebin is easily fended off with a mere kick.