Lizard lung in development (IMAGE) Princeton University, Engineering School Caption The lizard lung forms quickly by a leveraging simple mechanical process the researchers likened to a mesh stress ball, the common toy. As fluid fills the developing lung, the inner membrane pushes out against smooth muscle tissue. The muscle separates into a honeycomb-shaped mesh and the membrane bulges out through the gaps, creating the surface area needed for gas exchange. Credit Image courtesy Celeste Nelson and Michael Palmer Usage Restrictions n/a License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.