The tardigrades were part of a “lunar library” that Spivack’s foundation had put together. According to Wired, the package was about the size of a DVD and contained human DNA—including Spivack’s own—as well as 30 million pages of information on mankind’s knowledge and thousands of dehydrated tardigrades.

Tardigrades are known as one of the toughest creatures on Earth. They are microscopic, measuring about 0.012 to 0.020 inches in length, and can withstand temperatures of up to 304 degrees Fahrenheit and can survive being frozen alive. One tardigrade is known to have survived being frozen for 30 years. They can also live without water for up to a decade by shriveling up and placing themselves in a state of suspended animation—a trait DARPA is currently studying in the hope of preserving soldiers injured on the battlefield.