In this photo provide by the Berlin Zoo on Friday, Oct. 18, 2019, a person holds one of the Zoo's Panda twins at the Zoo in Berlin. Zoo Berlin's panda twins, born on Aug. 31, 2019, open their eyes for the first time. (Zoo Berlin via AP)

In this photo provide by the Berlin Zoo on Friday, Oct. 18, 2019, Panda bear Meng Meng holds one of her twins at the Zoo in Berlin. Zoo Berlin's panda twins, born on Aug. 31, 2019, open their eyes for the first time. (Zoo Berlin via AP)

In this photo provide by the Berlin Zoo on Friday, Oct. 18, 2019, one of the Zoo's Panda twins lay near a ruler at the Zoo in Berlin. Zoo Berlin's panda twins, born on Aug. 31, 2019, open their eyes for the first time. (Zoo Berlin via AP)