The girl comes to a small realisation.
The reality of the matter is, they are not. Stone cracks and chips and if you take a hammer to it, it’ll shatter like glass. But marshmallows, they can be as soft and squishy and sweet as they like because everyone knows that’s exactly what they are. And that's why people like them, because they do what they say on the tin.
It's always nice to have a rock in your life, but sometimes we forget that those rocks have their faults too. We over look them because we need something to depend on. Something that will always be there. A statue will erode away and turn to an unrecognisable pile of imperfect gravel and dust. A marshmallow will be consumed and part of it will travel with the person forever.
What I'm trying to say is, look for the cracks and chips in your rock. If you help fix them, you might turn stone into a marshmallow.