500-million-year-old alien-like sea creature discovered in Canada. It’s a new species

More than 500 million years ago, something in the ocean changed. Some creatures evolved to build their own hard-shelled exterior. Others grew to sizes never seen before as the amount of oxygen on the planet’s surface finally reached a level high enough for complex creatures to exist. Most important, for about 10 million years, the number of animals living in the ocean skyrocketed. It’s called the Cambrian Explosion, and it turned the largest environment on the planet from a vast open sea to a packed ecosystem. Some of the new...