They initially appear as rocks. A great source of Clue scroll (level-1 and 2)'s.
Charm Drop Rates
Rock crabs are very great way of training for members, which is especially true to those who are new or low leveled. They have high life points, but very low attack, strength, and defence.
Rock crabs are also good for training range, with an appropriate level of defence involved, but not always. Iron knives are effective to kill them quickly using ranged. You have to stand next to the rock to have it attack you. When they stop attacking, go in and out of the cave to the east.
No one likes crabs...
Clue scroll (level-2), Clue scroll (level-1), Starved ancient effigy
Coins (4-64), Bait (10), Empty oyster, Oyster (1-2), Oyster pearls, Opal bolt tips, Nature talisman, Cosmic talisman, Edible seaweed (2), noted Seaweed (1-7), Copper ore (3), Tin ore, Iron ore, Coal ore (2), Bronze pickaxe, Iron pickaxe, Iron javelin, Rune javelin (5), Nature runes (4), Spinach roll, Casket, Steel longsword, Gold charm, Crimson charm, Blue charm, Green charm, Spirit weed seed, Tarromin seed, Whiteberry seed, Ranarr Seed, Cactus seed, Marrentill seed, Rock crab carcass