OOPArt, from the acronym for out-of-place artifact, is a term coined by American zoologist Ivan T. Sanderson for a historical, archaeological or paleontological object found in a very unusual, or even an impossible, location. The term covers a wide variety of objects. They range from material studied by mainstream science, such as the Iron pillar in India, to so-called "forbidden archaeology" that is far outside the mainstream.
Critics regard many cases of OOPArt as the result of mistaken interpretation or wishful thinking, while supporters regard OOPArt as an indication that mainstream science is overlooking huge areas of knowledge, either willfully or through ignorance. While some artifacts have indeed been proven to be mistaken interpretations, a lot are still left unexplained and ignored by mainstream science, this site has a few articles of those OOPArts sprinkled around.
Of course if something doesn't seem very likely or probable to your expert opinion,
you can safely keep ignoring these strange things - mainstream science does if it doesn't fit in with their existing scheme! ;p
Burned history, censored archeology, we don't know anything... unless we search for it.
There is wonder in this world.