The largest organism on Earth, and probably the oldest multicellular organism, is named Pando. Kind of a cutesy name for such an impressive specimen, don't you think?

If you were to meet Pando -- which you could easily do, if you paid a visit to Fishlake National Forest in Utah -- it would look like a forest of Quaking Aspen trees. But if you happened to be equipped to do DNA testing on plant specimens, you would realize that all of the trees were genetically identical. That's because they're all part of the same tree, sharing a common root system. One tree springs from a seed, long ago, and spreads out roots; but then more trees erupt from those roots, and the process simply continues. Individual "trees" might die, but that's like you or me losing a toenail; Pando lives on. It weighs in at over six million kilograms, and is likely more than 80,000 years old (although it might be much older). I have nothing especially profound to say about Pando, I just think it's cool. But when you have arrow-of-time on the brain, everything resonates. Unlike most other multicellular organisms, there's no reason why Pando should ever die, absent dramatic external factors. As long as its environment remains hospitable, Pando could live forever. Monocellular organisms, of course, do this all the time; they split into "children" which are genetically identical (up to mutations), so it's legitimate to say that any given bacterium has lived for many millions of years. The birth/growth/death cycle is not absolutely necessary to the existence of life -- it's just useful, if life wants to avoid the very real possibility that the environment does dramatically change for the worse. Giving birth to children with slightly different genetic makeups -- and then getting out of their way, by dying -- gives the species a fighting chance to adapt and survive in the face of dramatic changes around it. (Update: some termites have a different strategy.) Meanwhile, Pando abides. Good for it.