Crinoids (feather stars) are frequently found in association with corals, yet the physiological and microbial interactions between these organisms remain poorly understood. Both corals and crinoids host symbiotic microorganisms, but the functional roles of these symbionts, particularly in deep-sea environments, are largely unexplored. This study characterizes the microbiomes of the deep-sea corals Desmophyllum pertusum and Solenosmilia variabilis and their associated crinoid Koehlermetra sp. (Thalassometridae) from the Campos Basin, Brazil, to investigate potential cross-host microbial interactions and their ecological implications. We used multiple approaches for this investigation, including amplicon sequencing surveys, genome-resolved metagenomics, and fluorescence in situ hybridization