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.

Q: Sentence1: Interestingly, a squid is also a mollusk. 
Sentence2: squids have a circulatory system with one or two hearts that pump blood.

A: squid
****
Q: Sentence1: a light bulb is used for seeing in the dark. 
Sentence2: light is required for seeing.

A: seeing
****
Q: Sentence1: Inside the stomach is the gastric mill that has teeth to aid in the digestion of food. 
Sentence2: mammals have teeth.

A:
teeth
****