The Toledo Zoo announced Tuesday its female polar bear, Crystal, had quietly given birth to a cub Dec. 9.

Zookeepers have had to observe the pair remotely through a video monitor in their den, where mother and cub will remain secluded until the cub is large enough to join her on display.

This mimics the behavior of wild bears, which typically give birth in December and do not leave their dens until the cubs are much stronger in March or April, according to Polar Bears International.

Leaving the den is just the beginning, however. Polar bear cubs stay by their mother’s side for up to three years before they are considered adults and able to survive on their own.

Crystal’s roly-poly cub is far from that point — zookeepers don’t even know its sex and can't check until it's big enough to be separated from its mother.

For now, though, it’s enough to watch the adorable pair snuggle in their den, where the baby seems fond of chewing on Crystal’s paws and rolling around on its back.