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.
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Question: Sentence1: All monkeys are mammals. 
Sentence2: monkeys conserve body heat with their hair or fur.

Answer: monkeys


Question: Sentence1: After about a week the larvae leave the nodules and continue to develop into adult worms. 
Sentence2: larvae leave the nodules and continue to transform until having reproductive organs.

Answer: larvae


Question: Sentence1: Fingernails are also made of keratin. 
Sentence2: keratin prevents injury by forming protecting plates over the ends of the fingers.

Answer:
keratin