Strange Worms Are Taking Their Place on Your Family Tree

Just before the atomic bomb drops on Hiroshima, the land below appears smooth as glass. The bomb falls on a grid of streets aligned between lazy rivers. In footage from 1945, the city’s exceptional stillness seems to give the explosion oxygen.

The calm before the storm is a standard trope for movie directors. Composers too. Without a prior silence, there is no “KaBoom!” Although they’d never admit it, scientists fall into the same storytelling trap. There’s no better way to emphasize a phenomenon than to clear the space around it.

Science is rife with dramatic entrances: the Big Bang, the origin of life, the origin of animals. Biology students learn that animal lineages blossomed in the Cambrian explosion, about 530 million years ago. Shrimp-like monsters named anomalocaris swooped through the seas, stuffing prey into voracious, donut-shaped mouths. Large worms that resembled penises—named priapulids after the Greek god of fertility—sifted nutritious snacks out of the water. Other animals hobbled along on spiky legs; their fossils look so strange that the paleontologist who discovered them named them Hallucingenia for their “bizarre and dream-like appearance.”