The Chicken is a small, white chicken that is a mob, which only spawns in Grass Biomes.
It is currently the only animal which can generate items. For the Chicken, it pops out Eggs sometimes. These Eggs can hatch into new Chickens, which makes more eggs per minute.
When the Egg is "used", it can either disappear or make a new chicken. Eggs can also be used at the Cooker, with a Red Mushroom and Corn, to make an Elegant Souffle.
There are also 2 masks, the Rooster and the (?) Rooster. The Rooster mask gives you an egg in spawn while the (?) Rooster gives you a living Chicken on spawn.
It is wise to lure the Chickens in a Farm Plot so that they can keep producing eggs for whatever needs you have.