The Huldufólk of Iceland are small elf like creatures that hide under hill, rocks and trees.
They are known to cause chaos when their natural environment is threatened by today’s technology. ie. People using graters to flatten their hills. Icelandic folk have created small houses built into rocks and hills for them.
The folklore behind them has been Christianized. The tale cites the Huldufólk are the unwashed children of Adam and Eve. They were bathing their children when the Abrahamic god showed up uninvited.
Adam and Eve, quickly hid the gritty children behind rocks and trees and eventually forgot about them altogether, leaving them to fend for themselves. They had fibbed to their Biblical god when he asked about all their children. So the Biblical god cursed their unwashed children leaving them to stay hidden forever. The Huldufólk blended with the land and never really aged due to their small size and the curse laid upon them by a tyrannical god.