Old Hardshell, The Bane of Fishermen, is a Unique Flesh Harvester found in the Upper Realm of Cursed Fate: Tidal Cave in Act IV of Diablo III.
In combat, it has the Orbiter affix. Upon death, it is guaranteed to drop Helm of Cranial Crustacean.
A bounty may be offered to kill Old Hardshell, in which case the secondary objective is to kill 100 enemies.