Or maybe that carbon based intelligent life that wanted our planet it's us.

We were almost wiped out after the first large impact. The impact that happened a few millennia after we killed all those awful looking smarty octopus that lived in this planet. But we could not defend against the large Comet, it come from behind the Sun and way too fast. We had minutes notice.

Some microbes survived...And here we are again typing on our keyboards. :-)