It was American naturalist and cryptozoologist Ivan T. Sanderson who invented the acronym OOPArt, which stands for Out of Place Artifact. These are objects of historical, archaeological, or paleontological interest that have been found in a very unusual place, are judged to be too advanced for their time, or that demonstrate the presence of humans before they were known to exist.
The acronym is rarely used by historians or scientists and is mostly confined to the terminology of cryptozoologists, advocates of ancient astronaut theories, and paranormal supporters.
Hoaxes Or History?
Detractors argue that some authors use questionable methods to interpret artifacts. They believe most OOPArts that have not proven to be out-and-out hoaxes are the outcome of either mistaken interpretation or an assumption that a particular culture couldn’t have created an artifact or technology due to its lack of knowledge or materials.
However, a few alleged OOPARTs are arguably unusual within the scientific mainstream, although not impossible for their time.