Rising temperatures and recent marine heat waves in the Mediterranean Sea have significantly altered the composition and structure of marine communities, affecting species performance, distribution, and interaction dynamics. In this study, we explored the spatial distribution and conservation status of Astroides calycularis, a threatened and endemic structuring coral species in the Mediterranean, by collating and synthesizing Local Ecological Knowledge (LEK) from scuba divers along the Italian coasts. As climate change is facilitating the expansion of native thermophilic species such as the fireworm Hermodice carunculata, we also collected data on the distribution of this corallivorous polychaete and its potential interactions with A. calycularis. Results showed that divers were already familiar with both species and generally perceived the presence of the coral positively. The compiled data extended the known distribution range of both species, including new records and a high degree of spatial overlap along the Italian coastline. Additionally, numerous observations of necrotic A. calycularis colonies were reported. Lastly, divers’ experiences over recent years reflected a clear perception of increasing sea temperatures, consistent with the occurrence of marine heatwaves in the region.