Over time the ears of elephants may develop a wide variety of notches, tears and holes. And each ear has a unique pattern of veins that (in a good photo) are visible on its surface. These patterns are a very useful feature, particularly when two elephants are otherwise very alike. You can use a combination of these characteristics to ID an elephant.
The edges of the ears of elephants may be smooth or have any number of size and shape notches out of them, which together create a unique pattern. The notches and tears are caused by wear and tear, though elephants with thicker ears seem to be less prone to damage.
The largest video and audio library of elephant behaviors.