Did you know that Mount Everest, the highest mountain on Earth, was...

The rocks near the summit of Mount Everest are about 450 million years old, and fossils of ancient marine organisms, including trilobites, crinoids, and brachiopods, have been found in these rocks.
These limestone rocks were formed in a warm, shallow marine environment during the Ordovician Period ((a geological period that lasted from about 485 to 444 million years ago)) when neither the Himalayas nor Mount Everest existed.
Later, when the Indian Plate collided with the Eurasian Plate, these ancient marine rocks were uplifted and eventually became part of the Himalayas.