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.

[Q]: Sentence1: Humans have collected and grown mushrooms for food for thousands of years.
Sentence2: humans have collected and grown porcinis for thousands of years.
[A]: Humans

[Q]: Sentence1: if fossils of a water animal or plant are found in a place then that place used to be covered by water in the past.
Sentence2: Fossils of a water animal or plant are located in water-laid sediments.
[A]: animal

[Q]: Sentence1: Light rays are focussed on the retina.
Sentence2: When rays are shined at the eyes, they enter an opening called the pupil.
[A]:
rays