Mantis shrimp in there (or not?)

[justinl]

I see no real evidence of a mantis. You heard no clicking which tells me that it probably wouldnt be the smashing kind of mantis. The other kind uses spears but is virtually impossible to get as a hitchiker. A smasher (more likely hitcher) will usually smash shells open, not pull hermits out. Spearers usually don't even bother with shelled things.

Have you tried staking out the tank? If you don't ever see anything unusual in the day, sit by the tank at night and watch and wait.

Did the old LR have anything in it that might have caused this kind of damage? Serpent stars? Big worms?