You may have heard that seashells can be found atop Mount Everest. There are no seashells, but there is evidence of long-ago ocean life embedded in the limestone at Everest’s summit: fossils, including those of crinoids, ancient underwater animals with tentacles and cone-shaped shells.

Called the “Qomolangma Limestone” by geologists, the summit rocks are limestone (grainstone) with fragments of common Ordovician marine invertebrate shells, such as trilobites, brachiopods, ostracods and crinoids.

At the tops of the highest peaks, like that of Mount Everest, it is possible to find 400-million-year-old fossils of sea creatures and shells that were deposited at the bottom of shallow tropical seas. Now the fossils are exposed at the roof of the world, over 25,000 feet above sea level.