They are perhaps the oldest lifeforms on the planet, and they are without a doubt the tallest. They are home to many species of plants and animals that rely on them for protection and shelter. They survived the ice age by migrating into protective enclaves, to flourish once again throughout specific regions of North and South America, and remote regions of China. They are the redwoods. Their bark can be up to a foot thick and contains tannins that protect them from fire. Redwoods are symbols of the forest environment; sentinels that reach for the sky for the sunlight and moisture they need to survive, a survival that is critical to the forest system.