Install cairo-dock-cairo-penguin-plug-in by entering the following commands in the terminal:
sudo apt update sudo apt install cairo-dock-cairo-penguin-plug-in
Cairo-Penguin plug-in for Cairo-dock
A collection of official plug-ins and applets for cairo-dock. . This plug-in adds a lively Penguin in your dock. Tux images are taken from Pingus, some other characters are available or can be added easily.