Multiple organisms especially those that live on land require a rigid framework to support their bodies off the ground and to maintain their shape. Skeletons also offer protection to delicate internal organs for example the skull protects the brain
Because Yuki started off with a bowl of ice right. She sat in the room and watched the ice melt, the ice melts when the temperature is to hot then she heats up the water on a burner and it vaporizes when the water gets to hot.
