Mine are tuxedo urchins. They cleaned everything now I worry there is not enough food for them. Raising magnesium will turn the GHA white and make it weak for removal and your cleaner crewI have had bad experience with urchins. Any other options? The one I have right now is starving and lost almost all his spines. hes been in a cave for a week now, probably dead. I dont understand how it could have starved, when theres so much algae. Its a pincushion urchin. I had a temperature drop by 10 F a month ago but he seemed fine then, so idk.