Photo taken on Nov. 24, 2020 shows illuminated Christmas decorations for the event "Polar Advent in the Wild Heart of the City" at Zagreb Zoo in Zagreb, Croatia. (Emica Elvedji/Pixsell via Xinhua)

Photo taken on Nov. 24, 2020 shows illuminated Christmas decorations for the event "Polar Advent in the Wild Heart of the City" at Zagreb Zoo in Zagreb, Croatia. (Emica Elvedji/Pixsell via Xinhua)

Photo taken on Nov. 24, 2020 shows illuminated Christmas decorations for the event "Polar Advent in the Wild Heart of the City" at Zagreb Zoo in Zagreb, Croatia. (Emica Elvedji/Pixsell via Xinhua)

Photo taken on Nov. 24, 2020 shows illuminated Christmas decorations for the event "Polar Advent in the Wild Heart of the City" at Zagreb Zoo in Zagreb, Croatia. (Emica Elvedji/Pixsell via Xinhua)