A circle shape in Madagascar I was seeing Madagascar on Google Maps and accidentally i saw a circle shape near Bebao. Coordinates are 17.4317443°E and 44.644248°S.

Please, to satisfy my curiosity, can you tell me why is this shape like a circle?
It is an extinct volcanic crater.
The location is not listed as one of the active volcanoes in Madagascar.

Simplified geologic map of Madagascar (reference) shows the crater to be mapped as basaltic / Gabbro lava,