I’m not suggesting that long-lived objects like planets, stars, or galaxies are part of a cosmic organism (although it’s tempting to jump to that place for fun). Interesting things could be happening on much more modest physical scales. For example, could the messy chemistry we see in fossil fuels on Earth – a smorgasbord of organic reactions, a seemingly tarry chaos – be simply a short-term view of a living system that functions across hundreds of millions of years? 

Or consider a chunk of complex rock, a mixture of minerals and carbon chemistry. It may be bathed for a billion years in cosmic rays and indigenous particle radiation. It changes over that timescale, electrons are freed and captured, slow, slow chemistry and structural variation happens. Your pet rock might be just that, except you’re living too fast to notice.

Of course, rather frustratingly, to make proper hypotheses for these options we need a robust definition of life, but to make that robust definition we may need to first know the extent of options for life in the universe. 

That’s why we need to both look for life as we know it, and at the same time keep track of the things lurking right in front of us. The trick is to maintain scientific rigor and skepticism while thinking out of the box.
Quelle: SCIENTIFIC AMERICAN