This clam may seem to be like the shells you’ve beachcombed on past family vacations, but this mollusk, found in Morocco, originated in the oceans of the Eocene era, which spanned from 56–33.9 million years ago. 

This era is named after the Greek words for “new” and “dawn,” reflecting the abundance of modern fauna that developed during this time. This means that this clam shared the warm waters with early whales and sharks.

When its shell was emptied, this clam underwent a process known as agatization, where the original organic material is replaced with agate, a form of quartz. Mineral- rich water seeps in, forming a microcrystalline quartz variant called chalcedony. This chalcedony then fills the hollow spaces of the fossil, creating a crystal cast.

Although it may resemble modern clams, you can add this ancient bivalve to your fossil collection, knowing it is millions of years older than those you’ve seen washed ashore.