15. A pebble on Mars is the size of a cannonball.
In late 2016, images of a smooth, spherical object were taken by NASA’s Curiosity rover. Alien enthusiasts insist that this proves that extraterrestrial life exists on Mars and that this is a weapon used in an intergalactic war. The real answer is much less complicated. This cannonball is a pebble that gets its smooth surface from wind erosion.
The Mars cannonball differs from the blueberries found by Opportunity. The blueberries are rich in iron and hematite, while the cannonball comprises magnesium, calcium sulfate, and sodium. The cannonball is roughly 5 millimeters in size, but the blueberries closely resemble BB pellets.