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 America and other western cultures, tradition dictates that the wedding ring goes on the fourth finger -- the one between your pinky and middle finger -- of your left hand. Simple as it seems, this practice actually has a rich and romantic history, lending the symbol even more depth.