What object is powerful and sought after in the Marvel Cinematic Universe films concluding with "Infinity War"?

Infinity Stones

Who notoriously coveted Naboth's vineyard? What animal changes color to blend in with its surroundings? Which animal's teeth never stop growing, making it chew constantly? How many rings are there on the Olympic flag? Which sauce is commonly served with sweet-and-sour pork in Chinese-American cuisine?