The correct answer is - Life forms existed during the Cambrian period.
The Cambrian period is a period when the life on Earth ''explodes'', lots of different types of animals and plants, as well as separate families of them, are evolving rapidly.
One of those creatures that appeared in this period was the Paradoxides pinus. It was a trilobite that lived during the mid Cambrian. It had elongated semi-circular shape. It had an exoskeleton, so its outside was hard, but inside was soft and boneless. Its body was divided in numerous parts in order for it to be able to move properly and be more flexible.