Australite "button" – Kalgoorlie, Western Australia

Australites are tektites found in Australia and are generally smaller than other tektites. They are usually dark or black and have basic shapes such as sphere, oval, boat, dumbbell and teardrop. One of the most famous and valuable shapes of australite is the so-called "button."

Its initial velocity was higher than that of other tektites, enough to carry it just outside the Earth's atmosphere. They then re-entered the atmosphere and underwent a rare secondary melting. The aerodynamic action of the air causes the melt thus produced to accumulate in the periphery of the flying tektite, producing the characteristic ablation rim. The whole process is called the ablation effect.

Interesting fact: NASA used the australite "button" shape when designing the return modules for the Apollo program in the 1960s.