The thick and curved, predominantly pink with a black tip beak of the greater flamingo (Phœnicopterus roseus) is unique in the ornithological world as it allows the filtration of water and mud. When it is closed, the horny growths that line the periphery of its upper mandible are inserted into the fine lamellae bordering its lower mandible, forming a true filter. A pipe-shaped space remains free for the passage of the tongue whose back and forth movement circulates the water inside the beak.