Ficopomatus enigmaticus (Fauvel, 1923) is a filter-feeding habitat former of the Serpulid Family. As many other invasive species his long-term establishment and its cosmopolitan habits made its real origin unclear. Comparisons with historical data revealed an overall decline of Ficopomatus populations especially in brackish waters and estuarine areas. These results highlight the need for a more detail monitoring activity at a local scale level, but it might hide also some intriguing secrets if considered from a conservation biology perspective and taking into account also the climatic variations occurring at a global scale. The most up to date works worldwide suggested that many episodic removals of the small Ficopomatus reefs yet occurred in the last few years, but the real causes of this events need to be further investigated to be really understood. This work is the result of a field observation occurred through expeditious methods in a transitional ecosystem of the Circeo Man and Biosphere Reserve. ...