"The relationship between the glomerulus and Bowman's capsule is like that of a fist punched into a balloon"
"The bowman's capsule is like a baseball glove and the glomerulus is like the baseball."
A good discussion is on this page.
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.