After birth, its back swells and hardens into a shell. Powerfully sprays foam from its mouth.
Shoots water at prey while in the water. Withdraws into its shell when in danger.
The shell is soft when it is born. It soon becomes so resilient, prod ding fingers will bounce off it.
The shell, which hardens soon after it is born, is resilient. If you poke it, it will bounce back out.
When it feels threatened, it draws its legs inside its shell and sprays water from its mouth.
— Pokédex entries (via PokeAPI)