instruction:
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.
question:
Sentence1: Coral reefs provide food and shelter to many ocean organisms. 
Sentence2: Coral Reefs Coral reefs are threatened.
answer:
Coral


question:
Sentence1: Fish are the first known true chordates. 
Sentence2: Fish are the first known animal with a backbone.
answer:
Fish


question:
Sentence1: Sand and mud are examples of sediments. 
Sentence2: layers of sand over the remains of organisms over time can create fossils.
answer:

Sand