intrinsic semiconductor crystal
"An intrinsic semiconductor crystal is like a sea with no air bubbles below the surface and no water droplets above the surface. A metal with conduction electrons is like a sea with no air bubbles but lots of sea spray far above the surface of the sea."
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.