Cambrian

The Cambrian period, around 541 million years ago, was a crucial time in Earth's history marked by a rapid increase in the diversity of life forms. Often called the "Cambrian Explosion," this era saw the emergence of many major animal groups with hard shells and complex structures. The environment was primarily marine, with new ecological niches leading to innovative adaptations. This period laid the foundation for modern animal life, and the fossils from this time are some of the earliest evidence of complex multicellular organisms.