The History of Art needs to extend its methodological foundations and its conceptual frameworks to the study of missing patrimonies or of those that have been somehow fragmented, destroyed or mutilated by acts of violence. It is necessary to analyze, in first place, the plural reasons which determined and determine those acts of brutalization of monuments and works of art. The importance of a crypto-artistic analysis thus becomes very relevant in the domain of Iconoclasm. Some cases of study that are patentable in modern and contemporary Portuguese art are presented, which help to highlight the growing pertinence of their practice, not only to record a memory of losses but also to strengthen the soundness of preservation policies.