Frogs with fangs, giant rats, and fish that grunt: These are but a sampling of the otherworldly creatures that explorers from Britain, the U.S., and Papua New Guinea discovered while exploring what some call the newest ‘lost world.’

Nestled within the kilometer-deep crater of Papua New Guinea’s extinct volcano, Mount Bosavi, explorers discovered an isolated, untouched jungle teeming with hundreds of unrecorded-till-now species.

Stretching 3km across, the crater sits far from the reach of humans on that island’s remote Southern Highlands. This lush jungle has seen few bipedal visitors since the volcano last erupted 200,000 years ago, which gave the area’s interesting new critters plenty of time to evolve in strange ways.

Among the more impressive new species identified was a giant wooly rat, which weighed in at 3.3 lbs and stretched 32 in in length; it could be the world’s largest (imagine one of those things in your tent). The team also identified 16 new frog species (one with fangs), and three new fish, including the Henamo grunter, which emits grunting noises from its swim bladder. Check out photos and narration from one of the scientists here:

As terrifying as fanged frogs and wooly rats might seem, the researchers reported that the giant rat showed no fear of humans, and one small marsupial called a silky cuscus got friendly enough to cozy up to a researchers shoulder.

Wish you could visit the lost world of Mt. Bosavi? If you’ve got more than basic cable, you’re in luck: The researchers brought a BBC Natural History unit along with them to record everything. Episodes of the three-part documentary will begin airing on the BBC this week.

— Jordan Olmsted

Lost World of Fanged and Giant Rats Discovered in Papua New Guinea (The Guardian)

Giant Rat Found in ‘Lost Volcano’ (BBC News)