Limpets are a type of marine invertebrate mentioned in the How to Train Your Dragon Book Series.
Limpets are referred to as marine gastropods (generically referred to as snails and slugs) with a particular round shallowly cone-shaped shell, somewhat resembling a human knee-cap bone, or "patella". The term limpet mostly refers to the Clade Patellogastropoda ('true' limpets), but can refer to other distantly related invertebrates with similar-appearing shells.
Limpets typically inhabit rocky coastal areas and tidal areas worldwide. Their primary diet is algae, though some species also eat seaweed. Limpets are motile, if a bit slow. An interesting anatomical feature are their "radula" - or feeding apparatus - which contains a bit of tissue somewhat resembling a tongue with teeth. This tongue of sorts is used to scrape algae from rocky surfaces. The teeth arise from biomineralization and incorporates iron ions, leading to the formation of the iron mineral goethite.
In the Book series, limpets are a food source of both Vikings and Dragons, but are a food of last resort. In reality, limpets are eaten by many cultures around the world, but is not as widespread in Western cultures as they once were.
They are often considered by Vikings to be disgusting as food, often to the point that consumption of them is used as a type of punishment.
Gobber often used limpets to threaten the Hooligan boys. They are often considered by Vikings to be disgusting as food, often to the point that consumption of them is used as a type of punishment.
|“||The next boy to speak has limpets for lunch for the next THREE WEEKS!||”|
|— Gobber the Belch|
|“||EVERYBODY IS ON LIMPET RATIONS FOR THE NEXT THREE WEEKS!||”|
|“||And on top of everything ... a two-mile run carrying a deranged dragon on my back ... and only a dinner of horrible limpets to look forward to at the end of it||”|
|“||YOU shut up or I will tear you limb from limb and feed you to the gulls, you winkle-hearted, seaweed-brained, limpet-eating PIG.||”|
|— Thuggory to Snotlout|
|“||All around there were crazy towers of limpet shells stacked up in piles perilously high, like so many fantastic sculptures. ... For years they [Skullions] had had to exist on shellfish, the limpet in particular because it was so plentiful.||”|
|— Book 2|
Toothless also uses the excuse of "lergified limpets" as a reason to find treasure-sniffing difficult while on the Isle of the Skullions. Despite that, Toothless finds something under the earth. Hiccup digs the spot to find the "most gigantic limpet shell anyone had ever seen."
|“||It's the most enormous limpet I've ever seen," said Fishlegs in awe. "I think you may have discovered a whole new species.||”|
|— Fishlegs to Hiccup in Book 2|
In Book 3, Gobber actually put Hiccup and Fishlegs on three weeks' worth of limpet rations for sinking their ship and failing a 'Board-an-Enemy-Ship' lesson.
Mashed limpets are mentioned in Book 4 as a possible cure for illness that Old Wrinkly might give you.
|“||If you were ill, you would go to Old Wrinkly and he would examine you, consult the gods, and then give you some perfectly disgusting medicine like rabbits' droppings in limpet goo that might or might not make you better.||”|
|— Book 4|