 The term "skrimsl" is Old Norse, equivalent to modern Icelandic "" and refers to "monster", however it was specifically used in the sense of "sea or lake monster" () in Konrad Maurer's book on Icelandic folk legends (1860).Jón Árnason remarked that there were non-believers of the worm in his time in the 19th century who offered the rational explanation that clumps of foam drifting past could be have been mistaken by false witnesses.Various other rational explanations have also been advanced.