The knockers are a variety of kobolds. They live in mines and are usually good-natured. With a knocking sound they point out where the rich veins are to be found. Although they are usually friendly towards miners, they can play strange tricks. For a knocker there is nothing funnier than to scare miners by changing its ugly face to something even more horrible, while performing strange dances.

A little piece of miners-food must be left for the knockers, or else they became mad and that would bring bad luck. Whistling and cursing they dislike as well and that is usually rewarded by the throwing of (harmless) gravel.

In the hundreds of abandoned tin mines in Cornwall, knockers are still waiting for miners to lead them to hidden, rich veins.

In Wales, they are called Coblynau (or coblyn) or Buccas, who are related to their cousins in Cornwall. The sound of their knocking brings good luck, a sign that a rich vein is near.

The German variety of knockers are called Wichtlan. These creatures are less helpful than the English ones and are more of a nuisance. They hinder the miners in their work by undoing their labor. The Wichtlein announce the death of a miner by knocking three times. At oncoming disasters they could be heard digging and imitating other sounds of mining.