"Vesicular" refers to structures that are small, bubble-like sacs or cavities. In biology, it often describes cellular components, such as vesicles, which transport materials within cells. These vesicles can carry proteins, lipids, or other molecules, playing a crucial role in cellular processes like secretion and metabolism. In geology, "vesicular" describes rocks that contain many small cavities formed by gas bubbles during solidification. For example, pumice is a type of vesicular rock that is light and porous due to these trapped gas bubbles. This characteristic can affect the rock's texture and density.