The image to your right might look crazy scary, but that creature is less than a millimeter--and probably poses no threat to humankind whatsoever, which is great, since they're nigh invulnerable.
What this is is the tardigrade, affectionately called "water bears" by some people for their similarities to our mammal friends and their love of water. They find their home on various types of moss, and they're far from uncommon. What is uncommon is their survival mechanism. They need water to stay active, so when it's gone, it is then that they enter a state of "suspended animation" causing them to be able to live without water for over a decade. In this state, they're able to endure intense heat (over 90 degrees celsius) and intense cold (near to absolute zero). Couple that with a strong shield against radiation, and you have a creature that could easily be counted as one of the strongest organisms on Earth.
So, it's pretty great that we've found such a crazy strong organism with a cute name and ironic strengths, but what can we learn from them? Or with them?
Their defense against radiation is particularly interesting, since radiation causes severe damage to DNA. Somehow, these tardigrades don't flinch at this. Proteins will help re-form its integrity, and its own defenses also help. Radiation resistance isn't a tardigrade-exclusive skill. Many extremophiles live in places with extreme radiation levels--caused by uranium-rich granite and radon gas. They've also developed systems in place to repair their DNA and shield a good portion of the radiation.
What is also fascinating about the tardigrades are what scientists have been testing it with, such as acetonitrile, a dissolving chemical present on Titan, as well as possibilities of survival on Mars. Of course, this idea of tardigrades living in these places is slim, since their suspended state would be the only state they could survive in.
Another feat the bears can do is completely dehydrate themselves--a bit confusing considering their name, but altogether astonishing when you consider them as living things literally frozen in this state where they thrive off of nothing.
The creatures are clearly impressive and could hold a lot of clues for human protection against radiation and other forms of astronomical injury--they're able to take a dose of radiation that's 4000 times the strength of a harmful dose for humans. Recent research put them in low Earth orbit, exposed to the extreme conditions of space, and most of them survived, and those that survived could even reproduce.