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.
The Fourth (Ring) Finger. In the US and much of North & South America, the ring finger is most commonly associated with wedding symbolism: a band on the right fourth finger indicates engagement, while a band on the left fourth finger indicates marriage.