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.

[EX Q]: Sentence1: Mollusks are invertebrates such as the common snail. 
Sentence2: Another common snail is the decollate snail.
[EX A]: snail

[EX Q]: Sentence1: Most water comes from precipitation. 
Sentence2: aquatic animals require precipitation to survive.
[EX A]: precipitation

[EX Q]: Sentence1: Mutation creates new genetic variation in a gene pool. 
Sentence2: Mutation creates new genetic variation in adult genotypes.
[EX A]:
Mutation