The Eye of the Sahara
Also known as the Richat Structure, it looks like a big wide eye, hence the name: the Eye of the Sahara. With a diameter of 40 km, the eroded dome-like structure was first interpreted as an asteroid impact.
After several studies, it was concluded by geologists to be a highly symmetrical and deeply eroded geological dome. The center of the dome consists of siliceous breccia, measured at around 30 kilometers.