This mollusk, found in Morocco, originated in the oceans of the Eocene era, which spanned 56–33.9 million years ago. This era is named after the Greek words “new” and “dawn” due to the abundance of modern fauna that developed during this time. That means that this clam shared the warm waters with the first sharks and early whales.
When its shell was emptied, this clam became agatized. When the soft parts decay, mineral rich water seeps in and forms a microcrystalline form of quartz called chalcedony that acts as a crystal cast within the hollow spaces of the fossil.
Though it may look like modern clams, add this ancient bivalve to your fossil collection knowing it is millions of years older than those you’ve seen washed ashore.