Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
The bodies of organisms can make a sedimentary rock. Plant bodies are lithified to become coal. When shells are cemented together they make a type of limestone. So limestone can be considered chemical or organic.


Question: What is formed when plant bodies are lithified?
coal
Coal.