It was announced on June 8 in the scientific journal Geology that paleontologists examining rock samples from a 2007 dig on the Alaska-Yukon border have found microorganisms dating back over 700 million years ago.  The tiny animals, called Characodictyons, are only 20 microns in length, about one-fifth the width of a human hair, but they are extremely complex-looking thanks to a surprising trait.  They are covered with their own mineral coating that features spikes and toothlike protuberances.  This may have led to the development of snails and other armored creatures.