The apple is used frequently as a meta object. Kids learn mathematics by counting apples because an apple is easy to abstract into nothing, so only the mathematics are remaining. Computer interfaces sometimes use a red ball or circle to show that there is an object, and this stems clearly from the apple. Apart from the abstraction, an apple can also be a whole world, for example when you are a worm. An apple is also round like a globe, creatures live on the surface and inside it. It's nothing, it's a house, it's a planet, and it can be portrayed by just a red circle if there is the need to do so.