TASK DEFINITION: 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. 
PROBLEM: A plant of animal dies in a watery environment. Is buried in mud and silt. Soft tissues quickly decompose leaving behind hard bones or shells. Over time sediment builds over the top and hardens into rock. As the bone decays mineral seeps in replacing it. Fossils are formed. 

SOLUTION: plant; animal ,soft tissues ,bones ,mineral ,fossils 

PROBLEM: Sediment becomes loose from the rest of the soil. The sediment rolls down hill towards a river. The heavy items sink to the bottom. The lighter items float on the top and in convection cycles. As the river flows the sediment is moved. The sediment gets dumped through tributaries into lakes and the ocean. The sediment keeps moving around the world in convection currents. 

SOLUTION: sediment ,river ,convection currents 

PROBLEM: Dissolution of limestone forms caves. Rain gets carbon dioxide from the air. When rain goes into soil it creates an acid. The acid dissolves the limestone along cracks. Some will dissolve enough to form caves. 

SOLUTION:
carbon dioxide ,rain ,acid ,limestone ,caves