yup! I had three small black urchins in my tank and the biggest one ate half of a open brain coral and the rest of the brain coral died because of it,I removed him and about a year later the other two urchins started grazing on my montiporias,zoa frags,and not to mention rearranging my rock work,causing corals to fall onto other corals.I finally removed the other two and will never have another one in my reef again!