These mischievous creatures appear on Christmas Day to return underground to the Epiphany thanks to the blessing of the waters and subsequently of the houses with holy water.
Their appearance varies from country to country. Sometimes they are huge, sometimes they are tiny. According to some they have human features, for others they have animal characteristics (fur, goat or donkey ears, monkey arms). They are usually male and have clearly visible sexual organs, have an unpleasant smell and fear the sun, fire, holy water. They go out and make trouble at night, giggle and stammer, feed on slimy creatures like worms, snails, and frogs.
They come out of their hiding places protected from the darkness and enter homes through the windows, chimneys, keyholes and cracks they find in the walls and around the doors. However, there are ways to protect yourself such as leaving a colander on the doorstep: if a Kallikantzaros approached for his misdeeds, he would instead decide to sit and count the holes until the sun rises, when he would be forced to hide. Furthermore, the Kallikantzaroi cannot count beyond 2 because 3 is a sacred number and by pronouncing it they would die. Another form of protection is to mark the front door with a black cross on Christmas Eve. To prevent the Kallikantzaroi from coming down the chimney, it is customary to burn a log large enough to last for 12 nights, until the Epiphany and their return underground.
What do the Kallikantzaroi do when they do not engage in teasing in the houses? Something far worse! They hide underground and saw the world tree so that it collapses with the Earth.
In some areas of Eastern Europe, the 12 days of Christmas are "unbaptized days" and the time of year when demonic forces (such as the kallikantzaroi) are thought to be at their peak. To make sure that children born in this period were not demons, it was once used to bring the feet of babies close to a burning flame to reveal any claws or to put the little ones in an unlit oven, in front of which a flame was lit. Will it have worked? Anyone who has a child of at least 2 years has legitimate doubts about it.