http://www.newsweek.com/giant-blob-africa-earth-core-mantle-anomoly-rising-1687664

Deep beneath Earth's surface, on opposite sides of the planet, sit two enormous blob-like structures spanning thousands of miles. And one of them, beneath Africa, is slowly creeping up towards the surface.

Scientists first spotted the two giant structures via seismic observations. These anomalies sit in the lowermost mantle, between around 400 and 1,600 miles below Earth's surface, above the outer core.