Ozone is the best example; it forms in the atmosphere through a series of complex, non-linear chemical interactions of precursor pollutants, particularly certain classes of volatile organic compounds (VOCs) and nitrogen oxides (NOx).
A great fitting example is ozone
A great fitting example is hydrogen
An animal has an object in it's mouth.
multiple people are swimming
two men stand in a courtroom
Children playing with magazines
There are some dogs that are fighting
The men are landscaping.