Watch Ricky's report for more about the Frozen Ark project
Extinct animals could one day be brought back from the dead, say a team of scientists working on a big plan to help save endangered species.
They've been collecting blood from threatened animals around the world and freezing it in a lab called the Frozen Ark in Nottingham, England.
Blood holds DNA, which has information about how the animal is built.
If a species were to die out, the DNA might one day help bring it back from the dead - a process called cloning.
Dr Ann Clarke from the Frozen Ark project said: "There is a very real possibility that we might be able to one day bring back an extinct or a very endangered species."
Last year, a team in Spain managed to create a clone of the extinct Pyrenean ibex, a type of goat. But the baby died soon after it was born.
Not everyone agrees that doing this is a good idea. There are no guarantees the technology will work and it's really expensive. Some scientists think it's wrong to mess with nature by cloning animals.
But Dr Clarke says that we need to act now to collect the samples, otherwise we could be left with no choices at all in the future.