Brown adipose tissue is present in small mammals (e.g., mice) and in newborn humans. Most of it disappears in adult humans. The cells in both types of fat are called adipocytes although they differ in origin, structure, and function in the two types of tissue.
On the left hand, index finger. It's not the index finger you wear it on. Left hand, ring finger. The finger that you would wear a wedding ring on.
In the Middle Ages, the wedding ring was worn on the right thumb, until King James VI levied a tax on people wearing wedding rings. He defined a 'wedding ring' as ...the bridelope of the riht puma.... To avoid paying tax, people moved their wedding rings to their left ring-finger. Yes, we've just made that up.