lipid bilayer
"A lipid bilayer is like a sandwich, one layer of bread on top and one on the bottom, with greasy mayonnaise in between."
"Water forms hydrogen bonds with individual phospholipid molecule. As a result, individual lipid molecules are free to move about within the membrane, so the lipid bilayer is like the "shell" of a soap bubble."
"Because the lipid bilayer is like an oil, the cell utilizes all sorts of other proteins and macromolecules."
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.