This is another attractive macro algae. It's pink to dark red with a whispy form that seems to flicker in the current. I don't have a great picture handy, but it's behind the coral in this photo: I've found that this algae will be a deep red in low light and tends to turn pink in bright light. Grows fast with high nutrient levels, though as with all algae, growth may be limited by lack of phosphates. This one doesn't tend to attach to rocks, so wedging it in a crevice or tying it down with string is recommended.