Alviniconcha
Alviniconcha is a genus of deep water sea snails, marine gastropod mollusks in the family Provannidae. These snails are part of the fauna of the hydrothermal vents in the Indian and Western Pacific Ocean. These and another genus and species within the same family ("Ifremeria nautilei") are the only known currently existing animals whose nutrition is derived from an endosymbiotic relationship with a member of bacteria from phylum Campylobacterota (formerly Epsilonproteobacteria) occurs as an endosymbiont of the gills of "Alviniconcha hessleri". Description. The size of the shell varies between 25 mm and 35 mm. The surface of the shell  is studded with hairs on the periostracum, Individuals variation in shell size and the arrangement of the hairs, but the variation does not correspond to individual species. Species. Until 2014, "Alviniconcha" consisted solely of the species "Alviniconcha hessleri", described in 1988. In 2014, increased recognition of genetic differences between populations resulted in the formal description of five cryptic species within the former "A. hessleri" that are morphologically indistinguishable from each other but that have consistent differences in mitochondrial DNA sequences. Species within the genus "Alviniconcha" include: