The EUROPA stamp issue refers to the biodiversity of European waters in support of numerous ecological authorities to preserve and protect aquatic environments. San Marino presents a value featuring the Triturus carnifex, crested newt, an urodelo amphibian about 15 centimeters long whose males, in breeding season, are characterized by a dorsal crest and conspicuously colorful livery. Larvae sometimes suspend metamorphosis by becoming adults but retaining "neotenic" features such as gills. The other value presents Scarodytes ruffoi, a small aquatic beetle that lives in clean rivulets and streams. Its presence in the San Marino territory is of some importance as it represents the northern limit of this species endemic to the Apennines. The background is dominated by the color of Chara vulgaris, a macroalga typical of clear, well-oxygenated bodies of water that, in size and morphology, looks like a real plant. Common in the San Marino territory, it is an important element for aquatic habitats as it provides food and shelter to various species of invertebrates and contributes to the oxygenation of the water.