When I bought caulerpa (macro algae) once, this tiny 1/4" bright green worm enjoyed crawling all around my refugium. Night after night I watched him explore, snack on the macro, and grow. Little did I know how voracious the Sacoglossa - Oxynoe viridis - slug's appetite was! It would seemingly bite into the stalk with fang-like teeth, causing the plant to 'bleed' out and die. It will rip off branches, which is be fine if those have time to grow anew, but this one guy easily outpaced the plant. Not Refugium-safe, if you keep caulerpa.