Vesicles appear in nature when they are produced within lava (extrusive aphanitic igneous rock) whose dissolved gases come out of solution (are released) due to the drop in pressure during an eruption. The resulting lava solidifies around the gas bubbles capturing their shape inside and outside the rock. Vesicles do not appear in intrusive (plutonic) rocks.

Very few meteorites contain vesicles and even fewer contain vesicles throughout the meteorite. Very small to medium-sized vesicles can be found in stony meteorites as part of the the trailing surface of the crust, within shock veins or impact melts inside the meteorite, and in very rare instances as part meteorite’s texture as seen in the Ibitira meteorite.

Since meteorites are very rare and difficult to find as a random event, and vesicles in meteorites are themselves rare, the presence of discernible vesicles as part of a rock of unknown origin is a definitive indicator the rock is not a meteorite and terrestrial (either natural or man-made). For example, the presence of large vesicles is very common in the slag produced as a byproduct of refining metals like iron, and this slag is one of the most common meteorwrongs.