Giant clam

This article has a calculator here. Calculators determine experience and costs based on real-time prices from the Grand Exchange Market Watch.

The giant clam is an ocean encounter that can appear anywhere on the ocean while the boat is moving, starting at level 40 Sailing. It is possible to interact with them before level 40 as a passenger on the boat of a player who does have the level.

When you feed it a tradeable item, it keeps that item and will attempt to transform the item into a pearl which you can take the next time you encounter the clam, alongside experience equal to 15 times your Sailing level. The pearl given is based on the value of the item you last put into the clam. If you do not take the pearl from the clam, the clam will still have the same pearl the next time you encounter it, meaning that there is no risk of losing a pearl due to missing the encounter.

If a stack of items is used on the clam, it will only take one item from the stack. Noted items are accepted. They must be tradeable.

After claiming a pearl, the clam will accept a new item immediately – no need to wait for another encounter. Pearls rewarded from clams cannot be placed into one. The clam disappears after one minute without player interaction.

There is a cooldown of at least an hour before the clam can produce a pearl on a following encounter after placing an item in it.

The pearl that is rewarded is determined by the true item value of the deposited item, upon which the shop value and alchemy values are based. In the below table the high alchemy values are listed instead of the true item values, as this is always 60% of the item value, and high alchemy values are more commonly known than true item values. The trading value on the Grand Exchange is not considered.

Each pearl is on the collection log, and at most one pearl can be obtained per encounter.

Pearl	Pearl High Alch value	Item High Alch Min	Item High Alch Max
Tiny pearl	300	1	199
Small pearl	600	202	996
Shiny pearl	3,000	1,005	1,920
Bright pearl	6,000	2,040	4,800
Big pearl	15,000	5,400	9,984
Huge pearl	30,000	10,200	19,200
Enormous pearl	60,000	20,400	49,800
Shimmering pearl	150,000	50,000	96,000
Glistening pearl	300,000	102,000	183,000
Brilliant pearl	600,000	240,000	480,000
Radiant pearl	1,500,000	540,000	N/A

The following are some relatively efficient items which are easy to obtain for each type of pearl.

Pearl	Example Item	Profit[a]
Tiny pearl	Coins	299
Small pearl	Rune arrow	553
Shiny pearl	Dragon javelin tips	2,289
Bright pearl	Red spiky vambraces > Camphor repair kit > Diamond necklace	4,404
Big pearl	Red d'hide body	9,245
Huge pearl	Amulet of glory (6) > Ring of wealth > Dragonstone amulet	19,787
Enormous pearl	Rune full helm > Rune sq shield > Rune battleaxe	39,384
Shimmering pearl	Dragon med helm > Ancient staff > Dragon longsword /Dragon scimitar	91,910
Glistening pearl	Orikalkum gravel	197,613
Brilliant pearl	Dragon sq shield	297,590
Radiant pearl	Heavy ballista /Ancient totem /Blessed spirit shield	484,279[b]

The following are alternative items for Ironman players that can be bought from shops.

Pearl	Example Item	Alch Profit[a]
Tiny pearl	Coins	299
Small pearl	Rune arrow	200
Shiny pearl	Adamant sword	920
Bright pearl	Mithril platebody	800
Big pearl	Mystic boots	5,000
Huge pearl	Rune pickaxe	−2,000
Enormous pearl	Meat tenderiser	16,840
Shimmering pearl	Dragon longsword / Dragon scimitar	50,000
Glistening pearl	Dragon battleaxe	100,000
Brilliant pearl	Shield right half	−150,000
Radiant pearl	Dragon metal shard	−300,000

Casting High Level Alchemy on the resulting pearl can be profitable depending on what item was given to the clam. Alchables are good candidates and often profitable for less capital investment. However, typical alchables don't have a high enough value to return the best pearls, which can be more profitable.

Item		Item GE price	Pearl	Pearl High Alch	Profit
	Ancient totem	997,579	Radiant pearl	1,500,000	502,250
	Blessed spirit shield	1,004,563	Radiant pearl	1,500,000	495,266
	Heavy ballista	1,015,721	Radiant pearl	1,500,000	484,108
	Dragon sq shield	302,410	Brilliant pearl	600,000	297,419
	Dragon battleaxe	119,202	Glistening pearl	300,000	180,627
	Orikalkum gravel	102,387	Glistening pearl	300,000	197,442

Players wishing to complete collection log slots can use a low-intensity method to spawn giant clams. This involves sailing back-and-forth over a long stretch of sea, ideally one with no aggressive NPCs on the route. One such route lies on the southern edge of the game world, running east-west from the merchant shipwrecks in the Southern Expanse to the large shipwrecks south of The Little Pearl. If set up correctly, the player's ship will collide with a shipwreck at each end. This method allows 5-10 minutes of AFK time in which clams (and other ocean encounters) may spawn. As long as a boat is moving, its speed does not influence the spawn chance or duration between spawns.