My favorite shadows are those of trees. Their branches, leaves, trunks, and everything else make each shadow unique, even when photographed on different days or at different times of day. The wind often contributes to their ever-changing shapes.
Trees are signs of life, and we should be concerned when we stop seeing them frequently, as it will be a sign that life is ending. I'm being somewhat extreme, but eventually, if trees disappear, all life will end.
