Issue with clam

[jroseberry]

I have had this clam for months and had no issues. The clam has done very well. Today I found my urchin carrying it around and had it right up against my elegance coral. Since the event the clam has looked like this. Any thoughts?

 

[DSC reef]

Unfortunately that clam is a goner. Could be the light but I'm not seeing new shell growth so the clam could've been on the decline despite good mantle extension.

 

[Uncle99]

Stung big time by the elegance....