The pit is similar to the outer core made up of liquid nickle and iron. Thus it is very heavy and creates our gravity. The tremendous pressure makes it solid. This represents the total land of the earth. Let's use this valuable earth carefully as it's the only home we have.
Nectarines are only available in the summer and fall.
Though the proportions are not as comparable. You can use one nectarine per person, per group of four, etc. I have also given this lesson as a teacher demonstration. This would be advisable with younger students if you are concerned about using knives in the classroom. This could be an introduction to a unit on our environment, recycling, pollution control, etc.