Acanthophora spicifera

Thallus brittle, spiny, greenish brown, yellowish to grayish purple sparingly branched or bushy, 8-10(-25) cm high. Branching irregularly radial. Main axes to 2-3 mm diam. Branches cylindrical throughout, smooth, without spines. Determinate branchlets abundant with short spur-like spines to 0.5 mm long, regularly and spirally arranged along main axes. Sporangia to 50×80 mm, tetrahedrally divided, in swollen, spiny, short branchlets. Spermatangial clusters plate-like. Cystocarps urn-shaped 850 mm long, 790-820 mm diam, develop in axils of spines. Holdfast small, disc-like, irregularly lobed. Growing on rocks and dead coral fragments covered with sand, often in tide pools, intertidal to upper subtidal.

Worldwide, tropical and subtropical waters of Pacific, Atlantic, Indian Oceans. In countries of the Asia-Pacific Region: Japan, China, Vietnam, Philippines, Australia and New Zealand, Pacific Islands.