Another of the feared illhveli (a.k.a. evil whales) of Iceland is the Skeljúngur, meaning Shell Whale.
There a fundamental difference between this a all the other illhveli: the skeljúngur is safe to eat, even tasty, hence this is most dangerous of the edible whales cruising the Northern Seas. Moreover, even if catalogued as evil, the Skeljúngur has helped humans on occasion. Notably, a young skeljúngur aided Hjalmper and Olvir in their battle against a vicious hrosshvalur (i.g., Horse Whale).
The Skeljúngur ragens from 20 to 45 m long. Whether it has teeth or baleen is unclear, but it's very fat and its flippers are short and funny looking. It also lacks dorsal fins, and its entire body is covered with shells that rattle as it swims. These shells make it itchy. In deep coastal waters, it will rub its head against rocks and the bottom to get some relief.
However, despite its portly appearance, it's a fast swimmer, diving vertically to reach the bottom quickly, and at times sleeping with its head to head sticking out of the sea while its tail points to the bottom.
A shell-whale will stop in the path of an oncoming ship, moving to obstruct the vessel’s course if the captain tries to avoid it. Skilled sailors should change their course fast enough to evade it, as sailing right onto it causes the whale to throw the ship and kill all on board. When destroying boats, it likes to strike them with its fins and tails.
The Skeljúngur's armor makes them impervious to most attacks, hence they are quite fearless, playing dead to entice prey within range.
Witness recounted that off the coast of Grimsey, a skeljúngur was brought on board of the whaling ship Minerva after being harpooned and believed dead. The seemingly dead whale, however, came back to life fully recovered, thrashing to left and right to be free until the whole of the boat was turned to nothing.
Skeljúngurs hate the sound of iron being ground and filed, it reminds them of harpoons and pain. If one of these whales hears that loathed sound, it will go frantic and beach itself to get away from it. Its secondary name of Svarfhvalur (Iron Whale), is derived from this aversion.
-Davidsson, O. 1900. The Folk-lore of Icelandic Fishes. The Scottish Review, October, pp. 312-332.
-Hermansson, H. 1924. Jon Gudmundsson and his Natural History of Iceland. Islandica, Cornell University Library, Ithaca.