The paper provides an overview of symbiotic relationships of echinoderms with each other and with other organisms throughout the Paleozoic era. The following groups of organisms are analyzed: cyanobacteria, corals (colonial and solitary), bryozoans, brachiopods, annelids, mollusks (gastropods), graptolites, as well as traces of symbiosis with organisms whose systematic position has not yet been identified. The criteria for establishing the lifetime or postmortem settlements of epibionts and the criteria for determining the type of symbiotic relationships are discussed.