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.

Sentence1: Instead, the body is covered with a protective shell of bony armor. 
Sentence2: Most mollusks have protective of bony armor.
armor

Sentence1: pathogens can cause disease. 
Sentence2: pathogens affects the immune system.
pathogens

Sentence1: Mitosis is cell division. 
Sentence2: mitosis is more complex in eukaryotes than prokaryotes.

Mitosis