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 are invertebrates such as the common snail. 
Sentence2: Another common snail is the decollate snail.
snail

Sentence1: Limestone caves displaying stalactites. 
Sentence2: Limestone caves are formed by depositions.
Limestone

Sentence1: if an animal sweats then that animal 's bodily water decreases. 
Sentence2: Human beings are group animals.

animal