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.

Ex Input:
Sentence1: Bryophytes occupy niches in moist habitats. 
Sentence2: Animals and plants that live in the same place and share resources form a community biome niche .

Ex Output:
niches


Ex Input:
Sentence1: Ice is frozen water. 
Sentence2: ice expands.

Ex Output:
Ice


Ex Input:
Sentence1: Animals, plants, fungi and protists are eukaryotes. 
Sentence2: Slime molds found on rotting logs are eukaryotes.

Ex Output:

eukaryotes