Oh, twin panda cubs, you grow up so fast.

The little guys or girls — that's still a mystery — are now 100 days old and just like proud parents, staff at the Toronto Zoo have captured each milestone so far on video.

To celebrate the twins' first 100 days, staff released a compilation video that shows the pandas grow. 

The twins were born Oct. 13, 2015 to mom Er Shun, one of two giant pandas on loan to the zoo from China.

Staff will reveal the pandas' names and genders sometime in the next few weeks. The zoo said it hopes to introduce the cubs to the public in mid-March.

panda cub 11 days old

One of the twin panda cubs when it was just 11 days old. (Toronto Zoo)