About 500 million years ago, a squishy, thumb-size sea creature did a little dance — waving its upper limbs around in the ocean in a never-ending attempt to ensnarl some tasty morsels floating by.

When parasitic worms make it into a scrotum, they have a ball—and dance like nobody’s watching. But in a hospital in New Delhi, India, doctors were watching. And they caught the dangling disco on film ...

Journalist Bonnie Burton writes about movies, TV shows, comics, science and robots. She is the author of the books Live or Die: Survival Hacks, Wizarding World: Movie Magic Amazing Artifacts, The Star ...