OR..could be the eel died of other causes and he was just cleaning up. I had a purple lobster that I thought killed my jawfish b/c I caught him eating him. Was about to return him, when(while I'm standing there) a CB shrimp lunges at my clown and takes a big chunk outta it, just like the marks on my jawfish. Not sure what other fish/critters you have in there but might not be the lobster. Or coulda just been something wrong with the eel. I really can't imagine a 6" lobster managing to trap let a lone eating a 10" healthy eel. That's like reversing the food chain lol. Can it happen, I'm sure it could, is it likely..in my opinion no.