Spider veins are tiny, thin veins that can be seen very close to the skinâs surface. They look like red, blue, or green spider webs just beneath the skin. Sometimes they are also described as looking like marble. Spider veins are caused by a backup of blood. These become nonfunctional, âdead-endâ veins.
While the fairy fly is the worldâs smallest insect, there a few runners up! For example, the feather wing beetle is only .25 millimeters long. Some scientists think these beetles may even be smaller than fairy flies, but for now, the fairy fly is considered by many to be the âsmallest insect!â.
Viroids are the smallest infectious pathogens known, consisting solely of short strands of circular, single-stranded RNA without protein coats. They are mostly plant pathogens, some of which are of economic importance.Viroid genomes are extremely small in size, ranging from 246 to 467 nucleobases.In comparison, the genome of the smallest known viruses capable of causing an infection by themselves are around 2,000 nucleobases in size. The human pathogen hepatitis D virus is a defective RNA virus similar to viroids.iroids were shown to consist of short stretches (a few hundred nucleobases) of single-stranded RNA and, unlike viruses, not to have a protein coat. Compared with other infectious plant pathogens, viroids are extremely small in size, ranging from 246 to 467 nucleobases; they thus consist of fewer than 10,000 atoms.