In the southeast of Romania, there is an ancient cave that has been sealed for over 5 million years – since our distant ancestors came down from the trees. Despite no light, low oxygen, and a poisonous atmosphere, it is teeming with alien-looking life including 33 unique species.

The primary producers of this subterranean world are different bacteria that oxidise sulphur, methane, and carbon dioxide in what is an entirely unique cave ecosystem. It’s not somewhere you’d want to go, as it’s teeming with strange insects with extra-long appendages to help them navigate the dark.

Perhaps even stranger is that it’s right next to the suburbs.