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: Cnidarians have a hydrostatic skeleton. 
Sentence2: Jellyfish have a hydrostatic skeleton.

A: hydrostatic
****
Q: Sentence1: Eggs are usually laid in a nest. 
Sentence2: birds have nests.

A: nest
****
Q: Sentence1: chemical weathering causes iron in rock to oxidize. 
Sentence2: Oxidation of iron minerals causes the redness of the rocks.

A:
oxidize
****