DavidReneke has a post on the Huge alien object at the south Pole.
Scientists believe a massive object which could change our understanding of history is hidden beneath the Antarctic ice. The huge and mysterious “anomaly” is thought to be lurking beneath the frozen wastes of an area called Wilkes Land. It stretches for a distance of 151 miles across and has a maximum depth of about 848 metres.
Some researchers believe it is the remains of a truly massive asteroid which was more than twice the size of the Chicxulub space rock which wiped out the dinosaurs. If this explanation is true, it could mean this killer asteroid caused the Permian — Triassic extinction event which killed 96 per cent of Earth’s sea creatures and up to 70 per cent of the vertebrate organisms living on land.
in other words, it was a lot bigger than the one that killed the dinosaurs. Wikipedia article here.
There has been a lot of discussion on what caused the Permian extinction: the latest theory had been the massive eruption of the Siberian traps, i.e. a major eruption of lava through cracks in the earth there.
2014 NYT article discussion here.
but of course, we all know what really is down there: