[Lamina, pl. laminak; this is a summary of the French Wikipedia article about the laminak, also spelled lamiak.]
In Basque mythology, a lamina is a humanoid nature spirit or genius; as a group, they are the laminak. Laminak are related to faeries and are described either as lutins, elves, gnomes, or trolls. They are mostly nocturnal creatures and live underground or near springs and streams.
Their appearance is uncertain. Females tend to be human-sized and have the webbed feet of a duck (sometimes chicken or even goat feet). In coastal lands, they may be represented as sirens. Their skin is sometimes described as copper in colour. Males are considered more gnome-like or dwarf-like with a very hairy body and face. In some legends, laminak are something in-between the two descriptions: small men with webbed feet, small women similar to other european fairies, etc.
It is said that laminak live underground and only come out at night because they do not like sunlight. They live in mountains and grottos, and are also to be found under bridges or near streams and springs, especially if thoses are directly connected to caves. They are untiring and talented workers, able to build whole houses, churches or briges between dusk and dawn. Women are excellent spinners with a spindle and distaff; some tales recount of their nocturnal going to the river for laundry.
The Laminak live in family households. They are frequently associated to gold and the garding of treasures. Females are described as combing their long hair with a golden comb near a spring or in front of their house. Their hair and clothes might also be golden. Two common themes in folklore are the gift of gold presents by the laminak, as well as the robbery of a golden comb.
They are ambivalent towards humans, sometimes being very generous (offering shelter, gifts) and other times extremely malicious (the rape of young women), with everything in between (vengeful beings, proposing services or pacts, etc). Some legends tell about the capture of a lamina maiden or the reverse, the laminak keeping a young human woman in their grotto. They are sometimes associated with sorginak (sg. sorgin, a wizard or witch who often assists the goddess Mari in her fighting against falsehood and lies). Like Mari, they punish liars and play tricks on them.
There also is a mutually beneficial relation between humans and laminak as the latter need human midwife assistance in childbirth as well as help in passing over at their death. They are generous to those who leave little offerings of food to them, providing with abundant harvest or doing little works.
Some tales speak of the impossible love between a shepherd and a lamina. In one of them, a young man fall in love with a young woman who turns out to be a lamina, which he realized only when he saw her geese feet. It is said that he died from his sorrow and that the lamina kept watch over his body, providing a shroud to cover him and accompanying the mourners (but did not enter the church).
Laminak are closely related to the pyrenean hadas or fadas (fairies) and their spouse the dragòts, sharing the webbed feet and common themes like impossible marriages and nocturnal laundry.