Image source, Chester Zoo Image caption, Bugio Island in the Atlantic, to which the snails have been returned after a breeding programme Published 19 minutes ago Zoo conservationists have bred 300 near-extinct tiny snails and introduced them back into the wild.
Just 21 Madeiran lands snails were found clinging to a rock on Portugal's Bugio Island.
They were believed to be the last of their kind.
Experts at Chester Zoo said they had to brave treacherous conditions and climb cliffs to return them to their natural home, which is part of the Madeira archipelago in the Atlantic ocean.
The Madeira government had asked the Chester Zoo experts to help with the snail conservation.
The conservationists had scramble from the water up a cliff face in the dark to find cracks in the rocks where the snails could be safely left.
Tamas Papp, assistant team manager for invertebrates at Chester Zoo, said: "We knew we had one shot to save them.
"If we missed this chance, that was it: they were gone." Image source, Chester Zoo Image caption, The snails were born in a breeding programme at Chester Zoo Papp added: "It might be the trickiest reintroduction we've ever done.
"We had a short window due to rough weather, and there's no jetty on the island.
"We had to jump straight into the water, climb out, put helmets and harnesses on, and start scrambling up the cliff face." Image source, Chester Zoo Image caption, Chester Zoo said conservationists had to battle rough seas and scramble up a cliff face The snails, which measure no bigger than a third of an inch or 8mm in size, are important as they eat vegetation and enrich the soil.
They will be monitored as they settle back into the wild.
