I got a Yellow Fiji Leather Coral (Sarcophyton elegans) in from Live Aquaria for my client. I placed it into the tank and they noticed these brown spots started showing up within two days. I had it low in the tank about three inches from the sand. The spots got worse the next day. This happened once before but last time I blamed it on a rock anemone that moved next to it. This time there was no anemones around. I prepared some reef dip. I removed it from the tank and I noticed these canals on the underside of the coral along with a lot of dead tissue. I dipped the coral for 8 minutes. I noticed a cap snail, nudi, and a scarlet hermit crab so I took them out of the bucket. I put the cap snail and the hermit crab back into the aquarium and put the nudi into a cup. I then pulled the coral out to look at the damaged tissue. I noticed this white crab. It had disk like legs and claws with small pincher on the inside end of the claw. I removed it from the underside of the coral which it was attached like a tick holding on with its legs not wanting to be picked off. I placed the into the cup with the nudi. I placed the coral back into the tank after removing the dead tissue. I called the client back the next day and the coral looked even worse. I told him that I saw so much damage that I didn't think it would make it and to remove it from the tank. It didn't make it. This crab is so small it is hard to get a good picture of it. It is half the size of a dime. The nudi is also very small 1/2". I took some of the tissue of the coral and is only feeding on the tissue. It will not touch any other food source. (Shrimp, pellet, algae, etc). I wonder if it only feeds on a certain type of coral.