This month, the world’s largest captive crocodile reportedly turned 120 years old. The croc, named Cassius, holds the Guinness World Record for its size — a whopping 17 feet, 11.75 inches long. The “birthday” is just an estimated milestone, according to researchers, as the crocodile was originally born in the wild.

“He was big and old when we caught him, and 38 years later, he’s still alive,” crocodile researcher Graeme Webb told the Australian Broadcast Corporation (ABC). “That’s giving us serious knowledge on longevity.” Webb was part of a team contracted to trap the crocodile back in 1984 by operators of La Belle Station, a pastoral lease in the Northern Territory of Australia that reported livestock losses. Cassius is also believed to have attacked boats in the area. His snout is slightly shorter, a common injury for crocodiles who attack outboard motors. 

By 1987, Cassius was sold to the MarineLand Crocodile Park in Green Island, Australia. According to the Department of Fisheries in Western Australia, crocodiles typically live up to 70 years in the wild and have been roaming this planet for around 200 million years. In captivity, crocodiles have been known to live up to 100 years.

“There is no way of knowing Cassius’ actual age as he was born in the wild and the age is just an estimate,” said Toody Scott, a crocodile keeper at Marineland Crocodile Park, in an email to Live Science. Scott admitted that Cassius’s birthday “was essentially made up a few years ago.”

In Australia, crocodile eggs are typically laid in November to March, with an incubation period of 80 days. In other words, it is improbable that Cassius hatched in June. Although Cassius’ birthday isn’t exact, he was likely already 30 to 80 years old when he was captured, so it’s not a stretch to estimate he’s over 100 years old and even 120 years old today.

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Croc longevity has been linked to their gut microbiome, which researchers say could provide anti-cancer, anti-microbial, and anti-aging properties to humans. Although much more research has yet to be done, crocodiles, and yes, even Cassius, could provide insight into how humans could live longer lives. And despite his age, Cassius is apparently as lively as ever according to his handlers.