500-million-year-old worm tunnels in NWT contain clues on life in early oceans

About 500 million years ago in what is now Northern Canada, the ocean floor was covered in a network of tunnels built by prehistoric worms. Some of the structures were inhabited by predatory worms that used slender, tube-like burrows to ambush unsuspecting prey. Others were made by species that inched through the muck looking to...