Euhadra peliomphala crawling on a tree trunk. This is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Bradybaenidae. This species is endemic to Japan, and exhibits exceptional geographical variation in its mitochondrial DNA.
As Euhadra peliomphala matures sexually, it develops a "head-wart" between the optic tentacles. The development of the "head-wart" parallels the development of the snail's reproductive system. The "head-wart" releases the steroid hormone, testosterone, throughout the body before mating.