Woolly Mammoths
When something dies in an area of permafrost, it is like dying in a freezer, their bodies can become entombed in ice, fully preserved. They can then appear again, centuries later, still perfectly preserved.
A baby mammoth was found near Magadon in 1977: https://blog.everythingdinosaur.co.uk/blog/_archives/2007/07/12/3087760.html
Mammoth tusks are very valuable & hunting for Mammoth remains is likely to be regulated in the near future: https://www.theguardian.com/world/2019/jul/14/permafrost-thaw-sparks-fear-of-mammoth-ivory-gold-rush-in-russia
With advances in DNA & cloning, some scientists think that extinct species can be reintroduced. First it was Dolly the sheep. Next it could be Molly the Mammoth...
Mammoth DNA cloned:
Visit Scientist's prehistoric mammoth "farm" near Chersky:
where they are working to clone the Woolly Mammoth:
https://reviverestore.org/projects/woolly-mammoth/progress/
Mammoth Museum in Yakutsk:
https://www.s-vfu.ru/universitet/rukovodstvo-i-struktura/instituty/niipes/mammoth/