Gigas Clam

This monstrous clam’s conjoined shells open wide enough to swallow a horse. Inside, two tubular siphons flank the thing’s innards, which resemble a fleshy, vaguely humanoid woman, save that instead of a face, it has a singular massive maw filled with rows of ravenous teeth.

Gigas Clam CR 11

XP 12,800
CN Huge magical beast (aquatic)
Init +0; Senses darkvision 60 ft., low-light vision; Perception +13


AC 26, touch 8, flat-footed 26 (+18 natural, –2 size)
hp 149 (13d10+78)
Fort +14, Ref +10, Will +8
DR 10/magic and slashing; Immune disease, poison


Speed 20 ft., swim 60 ft.; jet (300 ft.)
Melee bite +20 (2d6+9/19–20), 2 slams +20 (1d8+9 plus grab)
Ranged siphon dart +11 (2d6+9/19–20 plus poison)
Space 15 ft.; Reach 15 ft.
Special Attacks devastating bite, siphon jet, swallow whole (4d8 acid damage, AC 19, 28 hp), trample (1d8+13, DC 22)


Str 28, Dex 10, Con 23, Int 7, Wis 18, Cha 11
Base Atk +13; CMB +24 (+28 grapple); CMD 34 (can’t be tripped)
Feats Combat Reflexes, Improved Critical (siphon dart), Improved Lightning Reflexes, Lightning Reflexes, Point-Blank Shot, Precise Shot, Vital Strike
Skills Perception +13, Swim +27
Languages Aquan


Devastating Bite (Ex)

A gigas clam’s bite attack threatens a critical hit on a roll of 19 or 20.

Poison (Ex)

Siphon dart—injury; save Fort DC 24; frequency 1/round for 6 rounds; effect 1d6 Str damage and paralysis; cure 2 consecutive saves.

Siphon Dart (Ex)

A gigas clam constantly rolls collected sediment and calcifications into needle-like darts it can eject through its siphons. A gigas clam can fire one of these darts as a standard action at a maximum range of 100 feet with no range increment, dealing an amount of damage equal to 2d6 plus its Strength modifier, and possibly poisoning the target.

Siphon Jet (Ex)

As a full-round action, a gigas clam can use its powerful siphon to move a creature or object at least one size smaller up to 20 feet directly away from itself or directly toward itself in a straight line. A creature trapped in this stream of water can avoid the push or pull with a DC 22 Reflex save. A gigas clam can also use this jet to propel itself up to five times its swim speed in a straight line, and can use its trample attack in conjunction with this increased movement. If at any point during this movement the gigas clam comes in contact with a solid object (such as a ship’s hull), it deals 4d8 points of damage as it rams the object with its durable shell. The save DC is Constitution-based.


Environment any oceans
Organization solitary, cluster (2–5), or field (6–12)
Treasure incidental

Commonly found only in shallow beds of sediment on the ocean floor, the gigas clam is an unusual foe—one that often catches divers and sailors unaware when they mistake it for merely an over-sized mollusk. Shining, misshapen barnacles cover a gigas clam’s tough and distinctive shell, glittering nodes that attract curious fish toward the beast’s side. Even larger predator fish such as marlins, tuna, and sharks can find themselves in the tightly clasped jaws of a gigas clam.

Gigas clams are primarily sedentary monsters, content to lie in wait as prey inevitably wanders toward their seemingly harmless forms. Vast fields of the titanic bivalves can be found scattered along the ocean floor of the Inner Sea, feeding on fish and any debris that falls to the bottom, including shipwreck victims and castaways thrown overboard by pirates. If no food presents itself for some time, a bed of gigas clams either relocates or crawls toward land in search of a more dependable source of food.

Gigas clams depart from their mostly passive hunting style once per year, when the bulging summer moon is at its fullest. Entire beds of the creatures propel themselves upward and burst through the surface of the water, attacking passing ships as well as coastal communities.

During these times, gigas clams seek out their most favored prey: air-breathing humanoids. Using their powerful siphons to slam into passing merchant vessels and war galleons, the massive clams are indiscriminate in their search for humanoid flesh. Though they are normally hasty and seldom use tactics to obtain their prey, occasionally a lone gigas clam uses its feminine figure to trick unsuspecting ships into gigas clam-infested waters.

The clam and its kin ruthlessly ram the vessel until its contents spill into the open water.

Once trapped inside a gigas clam’s quivering and contracting musculature, victims are almost certainly doomed, as the clam’s acidic innards swiftly melt and destroy anything within. When engaged in melee, a gigas clam can strike with both its fleshy siphons as well as its terrible foot, which terminates in a toothy maw that can deliver devastating wounds.

Since gigas clams openly attack land-dwellers only during 1 month out of the year, coastal communities and fisherfolk dwelling near gigas clam beds know to prepare their ships and docks for the deadly onslaughts of these creatures. But even the most formidable defenses are not enough to hold back great numbers of the clams, and most find it easier to simply avoid settling near gigas clam fields. Particularly bold monster hunters and sages travel throughout the Inner Sea during the summer in hopes of spotting the slimy beasts, using elaborate charts and maps listing past reports of the creatures to pick which areas to observe. A few whisper tales of immense magical pearls buried within the clams, which they postulate are responsible for the clams’ increased size and intelligence. Others propose that the monsters absorb a portion of their victims’ intelligence and memories while digesting them.

Section 15: Copyright Notice

Pathfinder Adventure Path #60: From Hell’s Heart © 2012, Paizo Publishing, LLC; Authors: Jason Nelson and Rob McCreary.

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