Tardigrades, are also known as "water bears" or "moss piglets," are extremely tiny creatures (around 1 mm) that live in water. They are invertebrates with eight legs and can survive for up to 30 years without food or water. They can also live through temperature extremes from cold to very hot, and even can survive in the vacuums of space! Tardigrade researchers are still trying to figure out how they can survive in such extreme cases.
Tardigrades can survive conditions that would be deadly to any other forms of life. As mentioned, they can live from temperatures of -328 degrees Fahrenheit to more than 300 degrees Fahrenheit. Another superpower is that they can dehydrate their bodies into a state known as "tun." They retract their heads and legs and expel the water from their bodies. Scientists have found that tardigrades can be revived from this state after 10 years or more, and only a few hours after water is added! They can also survive radiation, boiling liquids, and pressure of up to six times the pressure in the deepest part of the ocean.
Rafael Alves Batista, co-author of a study at the University of Oxford, is very intrigued by tardigrades. Rafael and his colleagues wanted to explore the effects of potential astrophysical catastrophes and how tardigrades would react to them. This includes asteroid impacts, supernovas, and gamma ray bursts. Basically, in a nutshell, humans and animals would die, but tardigrades would survive. Researcher Thomas Boothby mentions that tardigrades are expected to avoid all possible extinctions, and only the death of the Sun will lead to the total extinction of them. Rest assured this will not be for another 6 billion years as the Sun is expected to turn into a red giant.
This past April, an Israeli spacecraft, known as Beresheet, crashed into the Moon during a failed landing attempt on April 11. It carried human DNA samples, dehydrated tardigrades, and 30 million small digitized pages of information about human society and culture. It is unknown whether the tardigrades survived the crash, but scientists think they mostly likely did and water would be needed to revive them. Only time will tell.