Starting around 540 million years ago during the Cambrian explosion many animal phyla, including the freshest of them all—bivalves, came into existence. Within ~100 million years, bivalves gained gills modified to filter feed, siphons to better breath, and a muscular foot to bury themselves into the sediment. However, for the last ~400 million years . . . → Read More: Can Bivalves Kick It? Yes they can!