The Importance of Earth Worms?

After a heavy rain, I walked outside and saw some pinkish soft worms. I was wondering where did they come from. Later when my parents were digging in the back yard to plant a small tree, I noticed that these worms are under ground. Immediately I thought since worms live underground, they possibly eat plant root and maybe that is what makes some plants die. So I started to remove the worms and throw them in the garbage can. 

Recently in a television program I saw someone who produces worms as her business. She was actually selling the worms to gardeners because worms are good for soil and plants. 

I was totally confused by now, so I decided to select this science project and find out how can the worms be good for the soil and how can someone make money from selling earth worms. I also want to know how we can identify the sex of the worm and how we can identify adults from children. Finally I plan to learn about the life-span and reproduction rate of earthworms.

 Project description
In this project you will research the benefits and problems of earthworms. You will learn about their living environment and research the effects of earthworms on soil and plant growth.
 Details of this project
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