Humans having any kind of sporting chance against hostile alien invaders armed with superior technology - Good luck. If they're advanced enough to cross the enormous distances of interstellar space, they're advanced enough to wipe us out without breaking whatever in their physiology passes for a sweat.

Here on Earth, we've found organisms that thrive in environmental conditions we would have once thought uninhabitable. The presence of these extremophiles suggests that life could potentially take hold on worlds other than our own.

It goes back to the starfish. That's when the light bulb really popped over my head. We'd found one on the beach, and I was struck by what astonishing creatures they are, talking with Dad about how they regenerate.