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. 
Q: A plant or animal dies in mud or soil. The bones are all that remains. Over time the bones are covered in sediment. The sediment becomes rock. The rock becomes a fossil. 
A: 
plant or animal ,bones ,sediment ,rock ,fossil 