The beautiful structure to the left is a reconstruction of the protein shell of the cowpea mosaic virus. This is a virus that infects the cowpea, a type of bean cultivated in warmer climes than the UK*. Viruses are the simplest form of life. They simply consist of a protein shell that contains and protects their genetic material, which is inside this shell. This virus’s coat is made of 120 molecules, of just two different types of protein – shown in green and yellow here. Inside are two molecules of RNA that cary the virus’s genes, plus a couple more proteins.