The Doctors Three
I do not know the name of the creature, but it was a butterfly-like creature a bit smaller than a Star Whale, I'd reckon. It laid an egg, giving the Earth a Moon to replace the one that had dissipated after it hatched, before it flew off into space. It was a marvelous sight to behold, the birth of a new creature.
Of course they don't. They simply see the threat and wish to eliminate it, thinking that will make everything better. But yes, that is something natural to many, if not all, races in the universe. Except perhaps the Daleks.
No, I was not there. I'd left, leaving the decision to humanity. It was one of those in-flux moments in time where I did not know the outcome, and I felt humanity should make the choice for itself, to determine their own future. One was readying the nukes, but Clara stopped her, allowing the creature to hatch.