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: Babies that are very large or very small at birth are less likely to survive. 
Sentence2: Poor nutrition while in the womb is the major reason why babies are small at birth.

A: birth
****
Q: Sentence1: Similarly, stars are referred to as suns, but our star is the Sun. 
Sentence2: our star causes water to evaporate more quickly by adding heat.

A: our
****
Q: Sentence1: Examples of monotremes are the Platypus and Echidna. 
Sentence2: Platypus and echidna lack a uterus and vagina.

A:
Echidna
****