Tarra and Bella. Two peas in a pod. Best friends forever. Sure, one is a four-ton Asian elephant and one is a stray dog. What of it? If you're looking for an explanation, there really isn't one. Why Tarra, an older elephant at a sanctuary in Tennessee, decided to pair off with a pooch instead of another pachyderm as most retired elephants do, we'll never know. What we do know is that they eat and play together, and that when Bella received a spinal cord injury, Tarra stood vigil for weeks outside a building while her pal healed. If part of being a great friend is remembering where one's loyalties lie, then Tarra is as good a pal as can be. Elephants never forget.