Definition: 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.
Input: Sentence1: Shelled animals and other marine invertebrates evolved, then fish, then jawed fishes diversified. 
Sentence2: Shelled animals and other marine invertebrates are not considered excellent predators.

Shelled