Overview Viroids are molecules of RNA that are not classified as viruses because they lack a protein coat. Taxonomy Navigation < Back to Microbiology Home ∧ Epidomain: Acellular Domain: Viroids ∨ Family: Pospiviroidae Referenceshttps://en.wikipedia.org/wiki/Virus https://en.wikipedia.org/wiki/Viroid https://en.wikipedia.org/wiki/Potato_spindle_tuber_viroid