What Little Furry Rodent Was Once Used to Make a Coat Using 200 of Them?

The little furry rodent you're thinking of is the chinchilla.

It's true that a single chinchilla coat could require the fur of up to 200 animals. This is because chinchillas have incredibly dense fur, with up to 60 hairs per follicle. Thankfully, due to ethical concerns and the rarity of chinchillas, chinchilla fur farming is now largely outlawed.