A groac'h (Breton for "fairy", "witch" or "crone", pl. groagez) is a kind of Breton water-fairy. Seen in various forms, often by night, many are old, similar to ogres and witches, sometimes with walrus teeth. Supposed to live in caverns, under the beach and under the sea, the groac'h has power over the forces of nature and can change its shape. It is mainly known as a malevolent figure, largely because of Émile Souvestre's story La Groac'h de l'île du Lok, in which the fairy seduces men, changes them into fish and serves them as meals to her guests, on one of the Glénan Islands. Other tales present them as old solitary fairies who can overwhelm with gifts the humans who visit them.