Also known as the cow shark it can grow to be over 5 meters long. It is actually the largest of its subspecies although this is probably partially due to the fact that most of its closest relatives are extinct.
https://en.wikipedia.org/wiki/Bluntnose_sixgill_shark
The bluntnose sixgill shark (Hexanchus griseus), often simply called the cow shark, is the largest hexanchoid shark, growing to 26 ft (7.9 m) in length.[2] It is found in tropical and temperate waters worldwide and its diet is widely varied by region.
| Hexanchus griseus (Bonnaterre, 1788) | |
 | |
| Range of bluntnose sixgill shark (in blue) |
The Hexanchiformes are the order consisting of the most primitive types of sharks, and numbering just seven extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens.[2]
Hexanchiform sharks have only one dorsal fin, either six or seven gill slits, and no nictitating membrane in the eyes. Shark teeth similar to those modern hexanchids are known from Devonian deposits in Antarctica and Australia, as well as Permian deposits in Japan. If these are in fact hexanchids, this may be the only extant order of elasmobranchs to have survived after the Permian extinction (and by extension, the oldest extant order of elasmobranchs).