At the right you see something that's hard to find on any other Web site: A fresh pile of chicken feces, also known as chicken manure, chicken poo and other names. It's about the size of the last joint in your thumb.
The nice thing about this picture is that it so clearly shows the white, pasty stuff on the right side of the dropping. That white paste is composed mostly of uric acid, and here's what's so wonderful about that:
Every second of the day and night, animals are producing waste inside their bodies, and many of those wastes are toxic. One of the most life-threatening of all such wastes is the chemical ammonia, NH3. As you can see from the formula, ammonia is a simple molecule consisting of only one atom of nitrogen bound to there atoms of hydrogen.
The bodies of us mammals quickly rid themselves of waste ammonia by combining it with carbon dioxide, CO2 to convert the ammonia into urea, CO(NH3)2, which is less toxic than ammonia, but still has to be removed from the body. This removal takes place when the urea is dissolved in water, and we urinate. Our bodies dissolve their urea in water, forming urine, which we can then urinate. In other words, when we go pee, we're flushing toxic ammonia from our bodies, in the form of urea. If we didn't, that urea would build up in our systems and we'd die.
Unfortunately, urinating also rids our bodies of water, which our bodies need. Solving this problem, reptiles and birds have developed a different, less water-wasting process for dealing with their bodies' ammonia. Instead of converting their ammonia to urea, they mostly convert it to uric acid, C5H4N3O3, which is excreted as a white paste or even a dry, white powder. Very little water is wasted. And that white, pasty C5H4N3O3, or uric acid, is what makes the right side of the chicken dropping white in the picture!
If our human bodies could convert ammonia to pasty uric acid instead of urea, we wouldn't have to drink nearly as much water, nor would we have to go pee nearly as often!