colt coral getting eaten

[urban79]

I have a colt coral that is being eaten by something. It looks like it has tears down the side and it is all shriveled. I do not see anything on it that could poosibly be the cause. I have not added any new fish. We have a yelloe tang, a six line rasse an orange spotted goby and a pink spotted goby and we also have 3 pajama cardinals. There is also a black tuxedo urchin and a black long spine urchin.
Does anyone have any ideas as to what the culprit might be? We have had this coral for almost a year and it has been doing great. We have recently had a problem with nudibranchs eating our zoas but we cleared that up.

[MKCindy]

Mine had shrivals around the base on one side. I found my tuxido sea urchan had dislodge himself and a frag on top of the colt. Appears he blamed the colt and left a few spines behind. I pulled them out (they kinda fell apart) and it recovered with in hours.