It is difficult to describe the appearance of the nix, as one of his central attributes was thought to be shapeshifting. Perhaps he did not have any true shape. He could show himself as a man playing the violin in brooks and waterfalls (though often imagined as fair and naked today, in folklore he was more frequently described as wearing more or less elegant clothing) but also could appear to be treasure or various floating objects, or as an animal—most commonly in the form of a "brook horse" (see below). The modern Scandinavian names are derived from Old Norse "nykr", meaning "river horse". Thus, it is likely that the figure of the brook horse preceded the personification of the nix as the "man in the rapids". Fossegrim and derivatives were almost always portrayed as especially beautiful young men, whose clothing (or lack thereof) varied widely from story to story.