Some people call themselves environmentalists. They think we must protect the natural environment, to keep it safe. Things in the natural environment that we value are called natural resources. For example; fish, insects, and forests. These are renewable resources because they come back naturally when we use them. Non-renewable resources are important things in the environment that are limited for example, ores and fossil fuels after a few thousand years. Some things in the natural environment can kill people, such as lightning.