Rock-shell shards are dropped by Giant Rock Crabs and King Sand Crabs. These are used to make rock-shell plates by giving the Skulgrimen 3 dagannoth hides, 10,000 coins, and 1 rock-shell shard.
Giant rock crabs are found in the Waterbirth Island Dungeon, while King Sand Crabs are located within the south-eastern section of the Catacombs of Kourend. Players may find King Sand Crabs more favourable to kill for rock-shell parts, due to the lower melee defence; it should be noted, however, that Giant Rock Crabs have a -10 Magic defence bonus, which makes magic more effective on them.
Dropping monsters[]
Monster Combat level Quantity Rarity King Sand Crab 107 1 Uncommon (1/64) Giant Rock Crab 137 1 Uncommon (1/64)