Something amazing has been discovered in Oklo deposit from Gabon, which used to be a French colony, that part belongs to the equatorial somewhere on the western side of Africa.
A french Uranium researcher and expert here discovered traces of 3 kind of uranium, 238, 234, and 235. However these particles of uranium had something different about them. Uranium-234 only had a concentration of 0.717, which is incredibly high compared to usual numbers.
That urged him to take more tests around that area, which lead to the discovery that Uranium had been scattered around everywhere in around 1km radius, he even found traces of it as far as 2.5km. This and many other tests led him and other researchers to believe that this was in fact a nuclear reactor of the past, which by carbon dating it shows us to be a lot older then we would think, although we are not quite sure yet.