instruction:
In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
question:
The animal dies and the body falls down. It is not eaten by anything. The body falls in a sandy or wet place. The soil forms around the body. Time passes on and the rock forms. Millions years later the fossil forms. A person now finds the fossil. 
answer:
animal; body ,soil ,rock ,fossil 


question:
Coal is burned at a furnace. The resulting heat energy is used to heat water. The heated water is turned into steam. The steam drives a generator. Electricity is produced. 
answer:
coal ,heat energy ,water ,steam ,electricity 


question:
Humans are born as babies. Babies become infants. Infants become children. Children learn skills. Children become teenagers. Teenagers undergo puberty. Teenagers become adults. Adults have children. Adults become elderly. Elderly humans die. 
answer:

babies ,infants ,children ,teenagers ,adults ,elderly