The researchers' solution is a complex series of tiny movements. First of all, when you look at a pearl way up close under a microscope, you find that it's not smooth at all; it's covered in tiny sawtooth-like steppes or terraces. The act of sticking the protein or chitin to the layers of aragonite, creating these terraces, imparts a tiny amount of energy. Water molecules around the pearl are warmed up, pushing off the little terraces and causing a tiny little bit of rotation in one direction. If the oyster was simply laying down entire coatings of nacre at once, this would have no effect, but the oyster instead does it in parallel lines, all in one direction, so the oyster very slowly and naturally turns, like a ratchet. Amazing!