The villi's function is to increase the surface area of the intestine. A larger surface area increases the efficiency of food and nutrient absorption within the gut.
"A few years ago I was sitting on a rooftop in New Delhi giving a little presentation. One of the chaps there was a doctor who nodded his head to say "this is just too obvious" while his wife, sitting at his side, just did not get it. I explained it twice then the doctor turned to his wife and said "Villi is like seaweed in the ocean. They wave in the water drawing nutrition into the plant. A storm then comes through, churns up the water, rips up the seaweed and throws it up on the beach. When the storm is over things settle down the seaweed re-grows and things go back to normal."
Or maybe they are like the roots of plant. They are a structure that has a very large surface area so that there is a maximum amount of chemical uptake.
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.