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. 

Example Input: Plants start growing on or near the rocks. The roots of the growing plants start to break up the rock. The plant acids dissolve the rock. The rock is broken down into smaller pieces. Erosion begins. 
Example Output: plants ,rocks ; rock ,roots ,smaller pieces 

Example Input: Gather the ingredients for the cake. Mix the flour, sugar, egg, and water to make batter. Pour the mixture into a cake pan. Place the cake in the oven to cook. Take the cake out when it is cooked through. Let the cake cool. Serve the cake. 
Example Output: flour ,sugar ,egg ,water ,batter ,cake 

Example Input: Some of the rock in the ground is made of limestone. Over long periods of time rain can hit the limestone. And cause a acidic reaction. The limestone will slowly disintegrate. A large gap with be where the limestone was. Result in the cave. 
Example Output:
rain ,limestone ,gap; cave