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 Q]: Sentence1: Ions are atoms or groups of atoms that carry a positive or negative electrical charge. 
Sentence2: An ion is formed after a neutral atom loses an electron.
[EX A]: Ions

[EX Q]: Sentence1: Sponges are filter feeders. 
Sentence2: Hawksbills feed primarily on filter feeders.
[EX A]: feeders

[EX Q]: Sentence1: if the amount of available food and water decreases in an environment then animals may leave that environment to find food and water. 
Sentence2: if the amount of available food and water decreases in an environment then humans may leave that environment to find food and water.
[EX A]:
amount