Grotta in Norse mythology, was a miraculous mill of king Frothi; it had two stones, so large that no one could turn them, but everything could be ground on it. In order to set it in motion the king had two maids; Menja and Fenja, who had come from Sweden. They were only allowed to rest so long as the cuckoo did not cry. When the sea-king, Mysingr, came, they ground. out an army or Frothi; but the army was conquered, and became a prey of the strange king, who took the treasures and the mill on his ship, aid ordered the maids to grind salt. This they did until midnight, and then asked the king whether he had enough, but Mysingr told them to keep on. They did this so long that the ship sank, and the sea was made salt.