Some materials contract when heated rather then expand as most materials do.
It decreased the amount of carbon dioxide in the air and increased the amount of oxygen because plants go through photosynthesis and convert carbon dioxide to oxygen in the process.
There are several ways you can categorize things. This is an example of how I would put animals in order
1. Porifera (sponges)...they consist of a simple cell arrangement
2. Coelenterata (e.g Jellyfish) have an actual tissue
3. Platyhelminthes they are more complex and have muscles
4. Insects. They have several organs that and a simple brain
