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: Mollusks live in most terrestrial, freshwater, and marine habitats. 
Sentence2: Clams live in freshwater habitats.
freshwater

Sentence1: Oil and gasoline are fossil fuels. 
Sentence2: lawn mowers convert fossil fuels into motion.
fossil

Sentence1: Coral reefs provide food and shelter to many ocean organisms. 
Sentence2: Coral reefs are nurseries of the ocean.

Coral