Hydroclathrus tenuis

Thallus net-like, fine, fleshy, irregularlylobed, near to spherical, sessile, irregularly vesicular when young and reticulate when old, light brown, yellowish-brown to orange-brown when old. The perforations 10-15 mm in diam., with inrolled margins. Net-like membrane (80)-250-300 μm thick. The cortex consists of pigmented, small cubical cells to 8-10 μm across. Medulla composed of several large, colorless parenchymatous cells, 70-80 μm diam. Attachment by broad holdfasts at many points. Surface hairs in groups at shallow depressions of the surface layer. Growing on lower subtidal dead coral fragments, rocks, or epiphytically on greater algae in sheltered areas.

Note. A source of polyphenolics.

Europe, Atlantic, Indian and Pacific Oceans. The Asia-Pacific Region: Japan, China, Taiwan, Vietnam, Thailand, Philippines, Australia.