It's ancient, it's massive, and it is faltering. The gargantuan aspen stand dubbed "Pando," located in south-central Utah, is more than 100 acres of quivering, genetically identical plant life, thought to be the largest living organism on earth (based on dry weight mass, 13 million pounds). What looks like a shimmering panorama of individual trees is actually a group of genetically identical stems with an immense shared root system.