The Wichtlein, a miner goblin from southern Germany, isn't necessarily an evil creature like most goblins, in fact they are very alike their English and northern German cousins (Knockers and Kobolds) helping or causing mischief to human miners and in certain cases, depending of the mine, they will guard it from anyone who trespasses their territory.
"They announce the death of a miner by tapping three times. When a disaster is about to happen they are heard digging, pounding and imitating miner's work."
Text in between "" is taken from the book "Faeries" by Alan Lee and Brian Froud.
This interpretation of the wichtlein is my own.
note: the human to the side of the goblin is as big as a bug.