 In theory, when the biological source (taxon) of an acritarch does become known, that particular microfossil is removed from the acritarchs and classified with its proper group.While the classification of acritarchs into form genera is entirely artificial, it is not without merit, as the form taxa show traits similar to those of genuine taxa—for example an 'explosion' in the Cambrian and a mass extinction at the end of the Permian.Acritarchs were most likely eukaryotes.