Gigantic predatory marine worms that lived about 20 million years ago ambushed their prey by leaping at them from underground tunnels in the sea bottom, new fossils from Taiwan reveal. 

These monster worms may have been ancestors of trap-jawed modern Bobbit worms (Eunice aphroditois), which also hide in burrows under the ocean floor and can grow to be 10 feet (3 meters) long. Based on fossil evidence from Taiwan, the ancient worms’ burrows were L-shaped and measured about 7 feet (2 m) long and 0.8 to 1.2 inches (2 to 3 centimeters) in diameter, researchers recently reported in a new study.