The Welsh version of the Cornish Knockers, these mine spirits were relatively good humoured, and helped the miners by knocking in places with rich lodes of mineral, or metal. The Coblynau dressed in miners’ attire, and stood at around 18 inches in height.
Belief in these mine spirits was once widespread especially in Celtic areas which were heavily mined, for example Wales and Cornwall. In Germany these mine spirits were known as Kobolds. It is easy to surmise that the dark, cramped, dangerous conditions of a mine, would be conducive to creating belief in supernatural creatures, and other superstitions.
Fairies were often thought to live underground in caves and in crevices.