Calcified algae, pink-violet color, fixed by small conical disk and forming dense tufts and elongated, with 50 mm high. Axes erect, to 180 µm diam., dichotomously branched several times, ending in small corimbiformes branches to 120 µm diam. The cladodes are much longer than wide. Monoecious species, with trigenetic biological cycle. J. rubens lives on exposed rocks and tide pools, situated between the average horizon of intertidal and subtidal threshold level, often epiphytic on other algae.