Elephant sharks, aka Australian ghost sharks, aren’t really sharks at all. They actually belong to a prehistoric group of fish called ratfish, which diverged from sharks about 400 million years ago. Creative Commons

The fish some humans are frying up and eating are actually related to us and can help us understand how our DNA evolved.

A type of fish called an elephant shark that is popularly used in New Zealand for fish and chips is “a very distant relative of humans,” the University of Otago said in a statement, and “has a remarkably similar DNA memory system to our own.” The key is a process called methylation, which controls how our genes express themselves.

Read: Hideous Fish Eats Things from the Inside Like an Alien

If we learn more about the vertebrates that share this DNA memory process with humans, it could help us understand how far back in our evolution it emerged and how.

“Our study identifies elephant shark as the most evolutionarily distant animal that shares this DNA-regulation system with us humans,” Julian Peat, one of the authors, said in the statement.

The elephant shark, official name Callorhinchus milii, is also known as the Australian ghostshark and can be found in the South Pacific Ocean near Australia and New Zealand.

A study in the journal F1000 Research found this fish performing DNA methylation suggests that process evolved before their common ancestor with humans branched off 465 million years ago although it likely evolved after jawed vertebrates developed 600 million years ago.

“The elephant shark is something of a living fossil — it’s the slowest evolving vertebrate we know of,” research leader Tim Hore said in the statement. But there’s still much more to learn: “So many things remain mysterious about the elephant shark — we don’t know whether this methylation memory persists across generations or if it contributes to how gender is decided.”

See also:

Two Extinct Reptiles Are Actually the Same Animal

Marine Reptile Fossil’s Short Neck Holds Ancient Clues About Evolution