Jingszo !

The Knocker, Knacker, or Tommyknocker (US) is a mythical, subterranean, gnome-like creature in Cornish and Devon folklore. The Welsh counterpart is the coblyn.

It is closely related to the Irish leprechaun, Kentish kloker and the English and Scottish brownie.

The Cornish described the creature as a little person 2 ft 0 in (0.61 m) tall, with a disproportionately large head, long arms, wrinkled skin, and white whiskers. It wears a tiny version of standard miner's garb and commits random mischief, such as stealing miners' unattended tools and food. 

Cornish miners believed that the diminutive Knockers beckoned them toward finding rich veins of tin. As miners changed from independent, family-owned operators to hired laborers for large industrialized companies, there was an increased concern for safety, reflected in the knockers new role. They knocked on the mine walls to warn of impending collapse.

Generally considered benevolent, they were also tricksters who would hide tools and extinguish candles.

They are similar to the coblynau of Welsh miners.