Why is the Plymouth rock important?

It really isn't, but a symbolic way to show the Pilgrims came to the new world. The story of the rock actually dates from an 18th century story. It wasn't until 121 years after the Pilgrims landed that a church elder said that his father who landed on the Mayflower landed on that rock. There is no historical evidence that the Pilgrims actually stepped onto the shore of Massachusetts on that rock. Bradford made no written entry about the rock. The stone has also been moved from place to place, split in two and broken by souvenir hunters.