The benthic ecosystem off the northeastern Adriatic coast is composed largely of clades characteristic of Sepkoski's Modern Fauna. However, across broad expanses of fine-sediment substrate, attached epibenthic suspension feeders strongly dominate in some areas and are co-dominant with mobile epibenthic deposit feeders in other areas. Preservation of skeletal residues in these areas would be composed largely of remains of attached suspension feeders. Therefore, although composed largely of Modern Fauna clades, the benthic ecosystem and its potential fossil remains reflect Paleozoic rather than post-Paleozoic ecology. This Paleozoic-style benthic ecology corresponds with low-nutrient water, low intensity of grazing predation, and relatively few endobenthic bioturbators, all of which were more characteristic of Paleozoic than post-Paleozoic seas. The thriving epibenthic attached suspension-feeding benthos in the northeastern Adriatic apparently results from the interaction of all or a subset of these three conditions.