Lacuna decorata is a species of sea snail, a marine gastropod mollusk in the family Littorinidae, the winkles or periwinkles. References Reid, D.G. (1989a) The comparative morphology, phylogeny and evolution of the gastropod family Littorinidae. Philosophical Transactions of the Royal Society of London, Series B 324: 1–110 Littorinidae Gastropods described in 1861