This review provides information on the synthesis and revision of the structures of natural dimeric (poly)hydroxynaphthazarins, metabolites of echinoderms and lichens, and on the refinement of the direction and mechanism of reactions in the synthesis of some of these compounds. Keywords: ethylidene-bis(2,6,7-trihydroxynaphthazarin); octahydroxymethyldibenzo[b,i] xanthenetetraone; mirabiquinone; cuculoquinone; islandoquinone; hybocarpone; mesocentroquinone; sea urchins; lichens; metabolites; tautomerism.