Medieval knights used to fight giant snails and no one knows why

Alright, that headline is a bit misleading. The knights were depicted fighting giant snails. But the mystery remains – why? And were snails really that big back then?

Apparently, it's a common sight in English scrolls dating from the 13th and 14th centuries: armored knights engaging in medieval combat with giant snails. Medievalists at the British Library began to wonder the same things we all are – WHY.

Two reasons might explain the ubiquitous depictions (but not fully). The first is that the snails are the enemy of the person writing the manuscripts. Many famous families and villains could have fit the bill. The only problem is that this doesn't explain why the knights are always losing to the villain. If this was propaganda, shouldn't the good guy win?

Another reason is that it could be a depiction of the common folk rising against an unwilling aristocracy. These slimy creatures from the garden weren't welcome guests in the manor houses and castles of the Middle Ages. Neither were peasants.

There's no way it could be a depiction of actual knights fighting real giant snails, right?

There were, in fact, snails as large (perhaps larger) than humans. But not in the middle ages. Fossils of Pachydiscus Seppenradensis – giant cephalopods – have been found in temperate climates from the USA and across Europe. This puts the snails in the area where they could have fought medieval knights, but the timing doesn't work out.

Fossil records date Parapuzosia back to the early-to-late Cretaceous period of Earth's history. This means these snails walked with dinosaurs like the Ankylosaurus and some species of dinosaur bipeds.

As far as history is concerned, knights couldn't have been fighting giant snails because snails just didn't grow that big back in the middle ages. Not even close. These days, the max size a "giant" snail grows can still fit in your hand.

So if they're not fighting actual giant snails, what's up with all the imagery of knights fighting giant snails?

If you have the answer, I'm sure the British Library would be interested in knowing.