"The Earth's layers are like an eye becuase the pupil represents the core of the Earth. The iris of your eye can represent the mantle of the Earth because it is ..."
many more in the link...
METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.