The Eye if the Sahara, also known as the Richat structure, is a geological wonder deep in the sahara desert. It has also been characterized as a geological bullseye and the exact origins and causes are not universally agreed upon.
The shape, spanning 50 km from edge to edge features zones of different erosions and is to flat for a meteorite impact and could be an eroded volcanic dome. The layers have eroded away leaving a shape of a peeled onion with many different layers of stone. The layers range from Proterozoic in the center to Ordovician at the edges. The whole area therefore displays rock that could have formed up to 2.5 billion years ago to 400 million years ago.
The structure shows all the specific characteristics of a maar, a low relief vulcano. Although today we only know of low volcanoes that are up to 8 km in size and usually they are filled with water, according to the origin of their name derived from the latin "sea". Maybe we are looking at the remains of a monster.