(MSN) – Scientists in Taiwan noticed odd, L-shaped burrows in a set of rocks eight years ago. Since the rocks once sat on the Pacific Ocean floor, they thought the tunnels had been made by shrimp, or perhaps octopuses. But the shape and structure of the burrows didn't match those made by such creatures, and the mystery lingered.
Now, it's been solved: The architects behind the tunnels were 6-foot-long worms that lived about 20 million years ago, according to a study published this week. Fossil evidence helped the study authors figure out how these predators hunted and built their undersea lairs.
According to their research, the ancient marine worms would lay waiting under the sand for unsuspecting prey; then when fish passed by, the worms would lunge out of their burrows, snag the swimmers in their gaping maws, and drag the victims under the seafloor. Collapsed sand around the tunnel mouths indicated the prey thrashed fiercely in the worms' grip.
Advertisement - story continues below