 The Iron pillar of Delhi was said to be "rust proof", but it has some rust near its base; its relative resistance to corrosion is due to slag inclusions left over from the manufacturing conditions and environmental factors.Supporters regard OOPArts as evidence that mainstream science is overlooking huge areas of knowledge, either willfully or through ignorance.Many writers or researchers who question conventional views of human history have used purported OOPArts in attempts to bolster their arguments.