Australite

Aerodynamically shaped australite; the button shape is caused by ablation of molten glass in the atmosphere during reentry.

Australites are tektites found in Australia. They are mostly dark or black, and have shapes including discs and bowls that are not seen in other tektites. NASA used the shape of "flanged button" australites in designing re-entry modules for the Apollo program in the 1960s.[1]

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