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: Many corals secrete an exoskeleton that builds up to become a coral reef. 
Sentence2: Good examples are Bubble coral, Elegance coral, Frogspawn and other Euphyllia corals.
coral

Sentence1: Minerals are chemical elements that are essential for body processes. 
Sentence2: minerals are needed by body processes.
processes

Sentence1: the volume of an object can be used to describe the size of that object. 
Sentence2: The volume of a physical thing can be used to describe the size of that physical thing.

can