A viroid is smaller than a virus. It is a strand of RNA with 246 to 467 nucleotides in length. It is single-stranded, with extensive self-bonding between bases and forms into a fluctuating rod-like or branched structure. It does not produce proteins, has no capsid or membrane, and hijacks cell enzymes to copy itself with a circular rolling mechanism. Thus far, viroids are only found in plants. Also, they can contain ribozymes, which are RNA regions that are able to accuratel