Not an official record, but tardigrades are, by far, the hardiest animal on Earth. They can survive boiling water, temperatures of absolute zero, pressure of the deep ocean, the vacuum of space, decades without water, and much more! In extreme conditions, tardigrades enter a state called cryptobiosis where they tuck in their legs and expel the moisture from their bodies, according to vox.com. They expel substances that create a type of nearly indestructible cocoon around themselves and reduce their metabolism by 99.99%. Tardigrades can last decades in this state, waiting until the environment is more hospitable. A group of physicists explored the reaches of what it would take to wipe out all life on Earth, including tardigrades, and came to the conclusion that there really isn’t much that could kill them all.