Length: 38 minutes. Did you know that millions of years ago Montana was home to a diverse array of sea creatures? This time period was called the Paleozoic Era, or Age of Marine Life, and it lasted from approximately 540 to 250 million years ago. Join Museum of the Rockies Paleontology Field Professional Lee Hall to explore strange animals like trilobites, sea lilies, huge armored fish, and dive deeper into Montana’s fascinating past.