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: Methane gas is a produced by rotting compost, trash, and human waste. 
Sentence2: Methane gas can be produced by Slime molds.

A: Methane
****
Q: Sentence1: Cells are the microscopic building blocks of organisms. 
Sentence2: proteins are the building blocks of organisms.

A: organisms
****
Q: Sentence1: Thyroid hormones increase the rate of metabolism in cells throughout the body. 
Sentence2: Metabolism is the process of converting food to energy.

A:
metabolism
****