The purpose of a letter of attestation is to confirm or acknowledge an action, statement or behavior. As such, it takes the format and layout of an official letter, but with a few modifications. Basically, the sender is attesting to the knowledge and awareness of a particular situation.
Some consider L.rubellus to be the true red worm. It is also called the dung worm, or red marsh worm. This worm loves manure and compost piles but has also been found working the earth which makes it doubly effective as the two other worm varieties stay mostly at the surface of the soil.
The worms are kept in a bin with shredded paper or other biodegradable bedding. You feed them food waste. They digest the waste and bedding then excrete nutrient-rich castings. After a few months, the castings combined with the well-decomposed bedding, become vermicompost -- one of the richest soil improvements around.