They will do that from time to time. Mine do it all the time and I for sure have enough shells in the tank. I think it's quite barbaric how they kill for the shells. I most likely will not be adding any more hermits because of it. I just buy them and they get killed off. :-(
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.