Rock lobster

Rock lobsters are found in Waterbirth Island Dungeon's fifth sublevel, room 16. They are similar to Giant Rock Crabs in the fact that they are initially disguised as large rocks, but they will attack the player as they approach. They have very high defence (though they are weak to magic attacks) and can hit up to 11. Their attack speed is faster than the Abyssal whip's and nearly as quick as darts, making them incredibly dangerous. Rock lobsters are commonly killed by rich, high-levelled players because of their common crimson charm drops. Using the right technique, killing Rock lobsters would be one of the fastest method of obtaining crimson charms in the game.

Obtaining crimson charms
An effective but expensive method of killing Rock lobsters is using the Ancient Magicks spells Ice Burst or Ice Barrage.

Armour and weapons

 * The best magic armour the player can afford, preferably Ahrim's robes, Mystic robes, Infinity robes or Sacred clay robes will suffice as well.
 * Amulet of fury or Amulet of glory.
 * Ancient staff is highly recommended for the magic bonus, though it is no longer needed to autocast spells due to an update. A water staff will do if the player does not want to bring water runes.
 * Unholy book.
 * Infinity boots or Wizard boots.
 * Barrows gloves or Infinity gloves.
 * God cape.
 * Ring of life because it is very easy to die here. If the player is confident, he should bring a Seers ring or Lunar ring.

Inventory

 * Death runes.
 * Chaos runes.
 * Water runes (not needed if bringing a water staff).
 * 50-100 Blood runes (to cast Blood Burst or Blood Barrage to heal off the lobsters if necessary).
 * 1-2 Rune thrownaxes (to knock down the props).
 * Proselyte armour (helm is not required), to wear while attracting the lobsters.
 * 1-2 Sharks or other high healing food (just in case) or Summer Pies, which restore energy and heal 22 hp.
 * Four empty spaces for charms.
 * Rest of inventory should be filled with prayer potions, the more the better.

Method
Rock lobsters are found in room 16, sublevel 5, the same area where the ladder to the Dagannoth Kings is. Protection prayers are highly recommended while travelling through the dungeon to avoid damage. The room is a long corridor that stretches a bit east, and then turns and extends south-west. When the player climbs down the ladder to enter the room, the Rock lobster near the ladder will attack. Protect from Melee should be activated, and then the player should run a little west to the edge of the wall and trap the lobster along the stalagmites (if this fails, run along the east side of the stalagmites, and then run back to the safespot). This is the safespot where the player will burst or barrage the lobsters. For now, the player may prepare themselves.

When the player is ready, they should don their Proselyte armour, activate Protect from Melee, and run east to the bend and about halfway down the south west path. The player should now have seven lobsters attacking them. The player can get two more if they want, but they won't follow the player to the safespot as it is out of their wandering range. There actually is a spot where the player can burst/barrage nine lobsters at a time, but it is more dangerous and harder to get into position than the safespot near the ladder.

Now the player should run back around the bend and return west to the safespot just south of the stalagmites near the ladder. It is important that the player stands directly south of the stalagmites and next to the west wall. Walking a pace south will "untrap" the lobsters, and the player may die in a matter of seconds if they do not activate Protect from Melee in time.

The player may burst/barrage the lobsters from one of several safespots. When all are killed, they should quickly grab the charms and go back to the chosen safespot. If the Rock Lobster that spawns near the ladder has already spawned, the player should activate the prayer before grabbing the loot. The player may repeat this as desired. 1000 casts of Ice Burst will gain the player around 200 crimson charms, 100 gold charms, and 50 green charms (blue charms are very rare from Rock lobsters). With Ice Barrage, the numbers nearly double.

Runes

 * Earth runes
 * Water runes
 * Pure essence (4, 8)

Talismans

 * Fire talisman
 * Air talisman
 * Cosmic talisman
 * Nature talisman
 * Body talisman

Charms
In order of commonness:
 * 2 Crimson charms
 * 2 Gold charms
 * 2 Green charms
 * 2 Blue charms

Other

 * 4 Seaweed
 * 4 Edible seaweed
 * Random amount of steel arrows
 * Random amount of iron arrows
 * Raw lobster
 * Uncut gems
 * Rune spear
 * Grimy herbs (Ranarr, kwuarm, cadantine, Irit)
 * Tinderbox
 * Level 2 clue scroll
 * Half of a key
 * Random seeds - onion, potato, watermelon
 * Fremennik shirt
 * Snape grass
 * Shield left half

Trivia

 * The examine is a reference to the B-52's song "Rock Lobster".