Penguin

Snow biomes are the only place they turn up, and they come in a few color variants. Any Bug Net picks one up, and it rides in your inventory until you set it down somewhere else, which is how you stock a pen at your base. They are fragile enough that a stray swing or a wandering enemy kills one outright, so clear the area before you start the chase.

The usual end point is a Penguin Cage, which is animated furniture and a one way conversion. Caging it consumes the critter, and the only route back is throwing the cage into Shimmer to undo the craft. It also goes into a Roasted Bird if you would rather eat it. Both are worth thinking about before you spend the only one you have caught.

• A Penguin Statue produces them endlessly, but statue spawned critters cannot be netted. Try it and the bird vanishes in a puff of smoke, which rules out the obvious farming shortcut.
• A blood moon flips every penguin in the world into a Corrupt Penguin or a Vicious Penguin, and Vile Powder or Vicious Powder does the same on demand. A decorative pen becomes a room full of hostiles after dark.

The bird inside the cage is not the critter sprite at all. The real penguin is too tall for the frame, so the game quietly substitutes the baby penguin pet. It is also one of only four critters with a banner of its own, alongside the Bunny, the Bird and the Goldfish.