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: Echinoderms use pheromones to communicate with each other. 
Sentence2: Echinoderms are known for their round symmetry.
[EX A]: Echinoderms

[EX Q]: Sentence1: hiding can be used for avoiding predators. 
Sentence2: Camouflage is used for avoiding predators.
[EX A]: avoiding

[EX Q]: Sentence1: Adult echinoderms have radial symmetry. 
Sentence2: deuterostomes have radial symmetry.
[EX A]:
have