A phallus-shaped worm that lived 505 million years ago is heads above the rest—it’s a “missing link” between two lineages of acorn worms, a new study says. Dubbed Spartobranchus tenuis, the odd creature is a type of soft-bodied marine animal that’s rarely preserved in the fossil record. The new specimen was first discovered in the early 1900s in an area called the Burgess Shale, a fossil-rich area in Canada‘s Yoho National Park.But the fossil went mostly unnoticed until a few years ago, when evolutionary biologist Jean-Bernard Caron of the University of Toronto “stumbled on drawers full of these worms” at...