What is the name of the part under the rooster's beak?

That dangley red thing hanging from under the chickens beak is call a wattle. It is the same material as the comb on the top of its head. Combs and wattles are attractive to other chickens of the same species and they also serve as little radiators to reduce heat in the chickens body. Blood gets closer to the surface of the skin in the wattle and comb and therefore cools as it passes through.