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: if an object is made of a material then that object has the properties of that material. 
Sentence2: An object is an item in the real world.
object

Sentence1: a fire requires oxygen to burn. 
Sentence2: Oxygen has  eight protons and eight electrons.
oxygen

Sentence1: Marine species live mainly in shallow coastal waters. 
Sentence2: Water species live mainly in shallow coastal waters.

coastal