Tag Archives: Earth's Surface

This Sponge Fossil May Be the Earliest Record of Animal Life

More than two decades ago, when Elizabeth Turner was still a graduate student studying fossilized microbial reefs, she hammered out hundreds of lemon-sized rocks from weathered cliff faces in Canada’s Northwest Territories. She hauled her rocks back to the lab, sawed them into 30-micron-thick slivers—about half the diameter of human hair—and scrutinized her handiwork under a microscope. Only in about five of the translucent slices, she found a sea of slender squiggles that looked nothing like the microbes she was after.