Why do Hindus worships rocks?

Why do Hindus worships rocks? Once Vivekananda went to Noth India to meet a king. The king asked him, “why do you pray to rocks?”. Vivekananda ignored the question and looked at a huge photo on the wall and asked King about that photo. King proudly said “That's my great father who killed millions of people in the war and won the war. He is my Role-model”. Then vivekananda took a near by smaller object and threw at the photo. King got very angry and was about to hit Vivekananda. Vivekananda laughed and said, “Oh king, its just a paper with some painting framed with wood..how can that be your father?” King didn't understand. Vivekananda said, “just like that painting is your father for you, every rock, tree, river, mountain is God for us. We believe God is everywhere”. A country's flag is in reality, just a piece of cloth, but it means the entire country for us. We salute to that flag.