The largest laryngeal cartilage is the cricoid cartilage True/False: The cartilage pieces get progressively smaller as you move from the trachea to the bronchi to the bronchioles True/False: Without the chemical surfactant in the alveoli, the alveoli will collapse True/False: Air enters the lung when the thoracic cavity decreases in volume

The study pushes back the clock on the origin of Earth's water by hundreds of millions of years, to around 4.6 billion years ago, when all the worlds of the inner solar system were still forming. Scientists had suspected that our planet formed dry, with high-energy impacts creating a molten surface on the infant Earth.

4.6 billion years.