A. spicifera has a large, irregularly shaped holdfast for attachment to hard bottoms. From the holdfast, erect fronds begin to branch out. The main branches have short, determinate branchlets that are irregularly shaped and spinose. Branchlets are hook-like, brittle and fragment easily under heavy wave action. Color is highly variable, and can be shades of red, purple, or brown (Littler and Littler, 1989). A. spicifera grows upright to approximately 25 cm.

Grows quickly in the aquarium