Knocker

This is my vision of a Knocker (or Knacker, or Coblynau), a category of underground sprite inhabiting the mines of Cornwall, Devon, and Wales, in Britain. They are generally described as small humanoids measuring between 45 and 90 centimeters tall, with a large head, long arms, wrinkled skin, whiskers, and miner's paraphernalia.

Mainly frequenting tin and coal mines, the Knockers however never allow themselves to be seen by the miners, and only manifest themselves by knocking on the walls of underground passages with their tools, hence their name. When they do so, they seek either to indicate a good vein to the miners, or to warn of an imminent danger, whether it is a landslide or a firedamp explosion ; the difference between the two types of signals is never explained, but we can conjecture that it is a question of time between impacts. To show their gratitude to these benevolent sprites and avoid future misfortunes, Cornish miners used to leave behind the last bite of their Cornish pasty. However, the Knockers sometimes show mischief, by blowing out candles, hiding tools, or stealing food. They may even frighten or attack anyone who tries too hard to find them out. Finally, Knockers cannot bear whistling, which may be due to an auditory hypersensitivity allowing them to better orient themselves in the mines ; thus, miners of the south of England are careful not to whistle underground.

They are considered underground cousins ​​of the Irish Leprechauns and the Anglo-Scottish Brownies, other benevolent representatives of the British "little people". But another version sees the Knockers as ghosts of miners who died while carrying out their duty, seeking to prevent others from sharing their fate.
Also, when Cornish and Welsh migrants came to settle in the United States in the 1820s, they brought their folklore with them. Those of them who worked in the gold and silver mines spread their stories of mine spirits as far away as California, so that even miners who did not share their origins came to believe in the existence of Tommyknockers, the New World cousins ​​of the Cornish sprites. The latter, like the Knockers, were sometimes considered as fairies, sometimes as ghosts.