Acanthophora muscoides

Thallus brittle, compact, bushy, cartilaginous, 7.5-18 cm high, dark brown-red, greenish or yellowish, to almost black, branching irregularly, more crowded (near to verticillate) in the upper portions. Main axes cylindrical, to 0.7(-2.5) mm diam. Short spines present both at main and determinate branches. The determinate branches spirally arranged. Sporangia in very spiny branchlets, tetrahedrally divided, to 90 mm diam. Cystocarps urn-shaped, 0.5-1.0 mm diam., with a large opening at their summit, solitary, on branchlets of the last order or in axes of spines. Holdfast flattened disc-like, irregularly lobed. Growing on rocks, sandy, muddy bottoms with stones and shells, intertidal to subtidal.

Atlantic (American coast, Caribbean Islands), Indian Ocean Islands, Pacific Ocean. Common in Japan, Korea, China, Australia and New Zealand.