The Diadema Long Spine Urchin, Diadema sp., is a useful herbivoric invertebrate that can be incredibly beneficial in helping control an algae problem as they are avid algae grazers. They are generally coral and reef safe but can occasionally nip at coral tips in search of algae. Their spines are mildly poisonous and can cause a slight skin reaction so be sure to handle with care. This species thrives best in tanks with plenty of live rock to explore and feed off of.