Snails are invertebrate animals mentioned minimally in the How to Train Your Dragon Book series.
'Snail' is an unscientific or informal term applied to Gastropod Mollusks that have a shell into which they can retract their bodies. Species commonly placed into this grouping may not have close phylogenetic relationships, other than being in Class Gastropoda. Snails can be informally subdivided into 'Sea Snails' and 'Land Snails', indicating where their species are found.
Being Gastropods, all snails are invertebrates (lacking bones) and have a large 'foot', or external body part to move and push on sediment. They typically have a defined 'head' region with eyes, which vary in complexity depending on species. Most snail species ingest plant material and Algae, but a few may consume animal tissue. Snails may breathe via simple lungs or gills; this is not necessarily reflective of the habitat they live in. Snails can be found in a variety of habitats ranging from deserts to deep ocean trenches, and many places in between.
In the Book series and in real life, snails are often referenced due to their apparently very slow movement.
In reality, snails are also eaten - one dish commonly heard of is 'escargot', a French preparation. Certain species of snails have been historically harvested for use as natural dyes, but is little-used in modern times. Some snail species can be a significant garden pest as well.
While the Viking initiates of the Hooligan Tribe are traveling via sleigh, Gobber the Belch snaps a whip over the heads of the Sabre-Tooth Driver Dragons pulling it, yelling at them to go faster and claiming he had seen snails move faster than they are.