caliburnus lived about 400 million years ago, during the Devonian period, in what is now Australia.
Both worms probably lived on coral reefs in shallow waters that are now part of the Australian mainland, the study authors wrote.
To learn just how well-protected these creatures were, the study authors took micro-CT scans of the worm fossils to create digital 3D models of their armor plates.The researchers found that the worms had two overlapping armor systems: one running down the length of each worm's skeleton, and the other covering both sides of the creatures.No longer lost to history, these two worms — Excalibur and Shuriken — can perhaps rest easier now knowing that tales of their dangerous and daring lives are still being told 400 million years later.Thank you for signing up to Live Science