Every high school biology student learns that the molecule that provides the energy for the metabolic requirements of every cell in living things is ATP. ATP is synthesized in the cell from a precursor called ADP. This process is catalyzed by an enzyme named ATP Synthase which is a tiny molecular motor of astonishing design. Here's a video that gives an idea of just how remarkable this protein motor is:
The narrator states that these structures are evolutionary impossibilities, but I don't know why he says that. All that had to happen was lots of mutations acting on lots of genes which control lots of proteins, a pinch of pixie dust, a wave of a magic wand, and a few miracles from mother nature, and anyone can see that motors such as these would be almost inevitable, even within the relatively brief window of time between the point when genetic material learned to replicate and the appearance of the first cells.
If you're skeptical it's because you lack faith in the power of blind, impersonal forces to do miracles. You need to try harder to convince yourself that engineering marvels don't necessarily require intelligent engineers. After all, if you put all the individual molecules that comprise a computer in a box and set it out in the wind and sun, after enough time there could be a fully functioning pc in the box. Just ask any Darwinian.
Thanks to Uncommon Descent for the tip.