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: All lizards are reptiles. 
Sentence2: Lizards are tetrapod vertebrates that produce amniotic eggs.

A: lizards
****
Q: Sentence1: Scientists still know relatively little about Archaea. 
Sentence2: scientists still know relatively little about non-bacterial prokaryotes.

A: Scientists
****
Q: Sentence1: Leeches are external parasites. 
Sentence2: Leeches are on the surface of the host .

A:
Leeches
****