One of the best charm dropping monsters in the game. To get to them you'll need a partner to help you through the first door of the waterbirth island dungeon.
Using multi combat spells from the Ancient spellbook is a common way of killing Rock lobsters seeing as though you can stack up to 9 lobsters in one pile and cast spells safely from various safe spots. Their melee and range defence is high, so magic is the preferred way of killing them.
It wasn't a rock... it was a rock lobster!
Clue scroll (level-2).
Water runes, Raw lobster, Edible seaweed (2), Seaweed (4), Snape grass, Steel arrows (6-18), Iron arrows (11), Steel legs, Pure essence (1-5), Tinderbox, Air talisman, Water talisman, Fire talisman, Earth talisman, Body talisman, Mind talisman, Nature talisman, Cosmic talisman, Chaos talisman, Earth runes (13-16), Water runes (2), Charms (2), Cabbage seed (2), Onion seed (3), Watermellon seed, Sweetcorn seed, Strawberry seed, Fremennik helm, Fremennik blade, Fremennik shirt, Fremennik shield, Lobster pot, Soda ash, Grimy herbs