Meet Mr. Mack, an Aldabra tortoise at Zoo Boise. He's a hefty fellow, and he's seen a whole lotta life. Endowed with an enormous domed shell, large claws and a long neck, these tortoises can grow up to four feet in length and 500 pounds in weight. And with the potential to live up to 150 years in age, these slow-moving guys boast one of the longest lifespans of any creature on the planet. Sadly, habitat destruction and climate change have left this species vulnerable.