Understanding how different disturbances and protection levels shape demography and the long-term viability of structural species is a challenge in marine conservation. In this study, we focus on the long-lived Mediterranean red coral Corallium rubrum as a model species. Due to the high value of its carbonate skeleton for the ornamental industry, C. rubrum has been intensively harvested for millennia. Nowadays, most of its populations at shallow depths remain functionally impaired and warming represents a new threat to the viability of this species. We used long-term photographic series over nine C. rubrum populations located in the NW Mediterranean Sea subjected to different disturbance levels to develop population projection models to address two questions: (I) What are the demographic processes underlying the extreme life-history strategy of C. rubrum; (II) Are marine protected areas (MPAs) an effective tool to preserve the long-term viability and functional dynamics of C. rubrum populations? The results were complemented with an extensive literature review of demographic studies of marine sessile species to understand the evolution of extreme longevities. The precious C. rubrum was at the slow extreme of the fast-slow continuum of marine sessile species, given its high survival and low reproduction success. Due to high survival of C. rubrum colonies, marine protected areas did not affect C. rubrum population's extinction risk. However, protection decreased partial mortality rates and enhanced the functional dynamics of C. rubrum populations. Our results provide important insights into the management implications for marine invertebrates with extreme life-history strategies.