Halimeda macrophysa

Thallus compact, erect, to 6 cm high. Basal segment small, subcylindrical or cuneiform, bearing fan-shaped or reniform segment, giving rise to 2 or 3 branches. The branches consist of series of segments. The branch segments moderately calcified, reniform, subreniform, 5-15 mm high, 10-22 mm wide, with thick upper margins. The upper segments dark green. Segments in the lower portion of thallus yellowish, pale greenish (because of hidden in holes and crevices and do not exposed to the sun). Utricles in surface view polygonal, large, (100)-110×180(-190) mm. Growing on carbonate base of coral reef (in crevices, holes from which only upper portions of thallus are seen), tightly adhering by small discoid holdfast to the substratum, in the middle and low intertidal pools.

Note: The alga is used in folk medicine.

Indian and Pacific Oceans.