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: Lancelet larvae are free-swimming. 
Sentence2: some larvae lack a hardened backbone.
[EX A]: larvae

[EX Q]: Sentence1: if a habitat can no longer support animals then those animals will move to another area. 
Sentence2: Each species of animal is unique.
[EX A]: animals

[EX Q]: Sentence1: Cells are the units of function in living things. 
Sentence2: living things cannot survive without oxygen.
[EX A]:
living