Cambrian Period, the first geologic period of the Paleozoic Era. It began 570,000,000 years ago and lasted 70,000,000 years. It is named for Wales (which the Romans called Cambria), where sedimentary rocks of the period were first recognized.
The sea scorpion may have been the largest bug to ever live on the Earth, according to a recent find. Learn more about the giant sea scorpion.
One grows from the ground and one from the ceiling, but sometime's it's hard to remember which is the stalactite and which is the stalagmite. How do they get there, anyway?