About 500 million years ago, the Grand Canyon was a great sea, and among the creatures it harbored was a newly discovered type of penis worm, armed with many rings of teeth. Penis worms are marine ...

Scientists have revived a worm that was frozen 46,000 years ago — at a time when woolly mammoths, sabre-toothed tigers and giant elks still roamed the Earth. The roundworm, of a previously unknown ...