The yak came to mind because of a delightful book we once read while studying Tibet. It was called Daughter of the Mountains by Louise Rankin, and after reading it we had learned quite a bit about yaks. Here are a few yak facts.
Yaks are tough and can endure high mountain altitudes and cold temperatures.
Yaks can be milked.
Yak milk can be made into balls of butter.
Yak butter milk balls can be strung together on necklaces for a portable lunch in Tibet (or they were at one time anyway.)
Yak butter balls are often enjoyed in cups of hot tea.
This is all making me hungry, and making me want to take a trip to Tibet. Maybe next summer.