Male muskoxen near Prudhoe Bay in Alaska, USA

Muskoxen are built to chill. These animals can endure, even thrive, in some of the harshest conditions on Earth during the Arctic winter. Their long, wiry outer coat covers a soft and thick inner layer, called qiviut, that keeps them toasty even as temperatures plummet. When winter ends, the muskoxen shed this undercoat, which is collected and spun into yarn that's warmer than sheep's wool and softer than cashmere - pricier, too.

Muskoxen, named after the strong odour the males emit during the rutting (mating) season, have roamed the tundra eating roots, mosses and lichen for thousands of years. In the 1920s, they were nearly hunted to extinction, and were totally wiped out in Alaska. But thanks to a reintroduction programme, there are now roughly 5,000 muskoxen in the US state, out of an estimated 125,000 animals worldwide.