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: Coral Reefs Coral reefs are widely distributed in warm shallow waters. 
Sentence2: warm shallow waters provide food and shelter to many ocean organisms.
[EX A]: shallow

[EX Q]: Sentence1: Leeches are external parasites. 
Sentence2: Leeches live on the surface of their hosts.
[EX A]: Leeches

[EX Q]: Sentence1: Birds move their wings using muscles in the chest. 
Sentence2: birds fly using muscles in the chest.
[EX A]:
Birds