Tooth and Nail

Sometimes I wonder how people and animals grow teeth and nails.  I mean, they only eat plant and animal material, so where do they get the tooth material?

Yes, I understand that food is broken down into its most basic molecular components then rebuilt to form structures, but it still amazes me.  

Similarly, trees take in sunlight, water, and nutrients from the ground, and they are able to produce wood to form their structure.  Wood is such a useful material that we plant and cut down trees in order to get it.  It's almost as if farm plants and animals are little factories to produce materials.  

The next step is to genetically program custom plants and animals to produce materials that we want.  From silk to wool to milk, just imagine all the materials that could be produced by an animal that has yet to be created!

We have oil-eating microorganisms, but can we make one that produces oil?  If you want to make tons of money and change the course of human history, create that organism.  I'll happily take 0.1% of the profit for providing the idea.