A persistent is a type of organism that has persisted for millions of years without noticeable change.

From the Latin persisto - to persist, to continue to stand.

Organisms that retain constancy of appearance in the process of evolution, i.e., that pass without significant changes from one epoch to another. Such forms are often called "living fossils" or phylogenetic relics. Examples: the spittlebug of the genus Lingula, the swordtail of the genus Limulus, existing for about 400 million years; the marine mollusk of the genus Neopilina - 350 million years; the brush-finned fish Latimeria - about 250 million years, the cephalopod mollusk Nautilus. In all cases, such a long preservation of practically unchanged forms of organisms is associated with the stability of the main components of the conditions of their existence.