I was given this red macro algae, and was told it is Red Chaeto(morpha). Since its prickly structure looked nothing like Chaetomorpha, I contacted a few algae experts for help. What it actually is is Caulacanthus ustulatus, but what matters more is knowing that it is an invasive species that we do not want in our tanks. It breaks up very easily into tiny pieces, and takes root anywhere it lands. Fortunately for me, it didn't live long in my refugium. Not Reef-safe, nor refugium safe.