 Critics argue that most purported OOPArts which are not hoaxes are the result of mistaken interpretation and wishful thinking, such as a mistaken belief that a particular culture could not have created an artifact or technology due to a lack of knowledge or materials.In some cases, the uncertainty results from inaccurate descriptions.For example, the Wolfsegg Iron was said to be a perfect cube, but in fact it is not; the Klerksdorp spheres were said to be perfect spheres, but they are not.