The discovery of tiny, cave-dwelling animals measuring just 4mm in length has halted plans to develop a $10bn (£5bn) mine in Western Australia.
Troglobites are found in caves in many parts of the world
Environmental protection officials rejected the iron ore mine proposal from mining giant Rio Tinto when 11 species of troglobite were discovered.
The troglobites are tiny cave-dwelling creatures which resemble spiders.
They feed on organic matter deep underground and will die if exposed to ultraviolet light outside their caves.
The chairman of Western Australia's Environmental Protection Authority (EPA), Wally Cox, said the proposed mine would cause the extinction of at least five of the newly-discovered species.
A Rio Tinto spokesman said the company would appeal against the decision.
"It's just part of being in the mining business," said the spokesman. "We support the EPA process in general."
Opposition environment spokesman Steve Thomas said the EPA ruling put future developments in the state at risk.
"Because [the government has] upgraded the requirements of the mining sector in the environmental approvals process to find what's out there, they go out there and find things," he said.
Troglobites have no eyes but have long front legs or feelers to find their way around in the dark.