Life may have begun in proton-powered rock pores. If you look at what all living creatures have in common, it's less than you might expect-- in particular, the cells membranes aren't similar, and pumping protons might be a more basic energy source than chemical bonds.
It's at least conceivable that the first life was in serpentine (a mineral-- if there's a garden of Eden pun in there, I couldn't find it) rock in the early, acidic ocean. It had DNA, RNA and proteins, a universal genetic code, ribosomes (the protein-building factories), ATP and a proton-powered enzyme for making ATP. I have no idea how or why it would have grown a skin.
And I'm wondering if this is part of the Fermi Paradox-- any old watery planet could have a primordial soup, but what are the odds of the right sort of rock in the right sort of ocean?
Link thanks to andrewducker.