Happy National Fossil Day and Happy Hagfish Day! To celebrate, I'm sharing a video about the closest animals to hagfish that are important as fossils, conodonts. Watch The Most Useful Fossils in the World from PBS Eons.
For decades, one of the most abundant kinds of fossils on Earth, numbering in the millions of specimens, was a mystery to paleontologists. But geologists discovered that these mysterious fossils could basically be used to tell time in the deep past.I've shown this video to two of my classes. My geology classes watch it because it serves as a good explanation of index fossils, while my organismal biology class watches it because it describes a lost piece of biodiversity. Besides, I think it's cool.