instruction:
Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
question:
Sentence1: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past. 
Sentence2: Common fossils include plant fossils like ferns.
answer:
plant


question:
Sentence1: folding an object causes that object to change shape. 
Sentence2: Folding an object causes that object to transform.
answer:
causes


question:
Sentence1: If the pH level is higher or lower, aquatic life is endangered. 
Sentence2: Aquatic life is endangered if acidity is higher or lower than a narrow range.
answer:

aquatic