Crabs, Jewel Crab

Medium beast, unaligned

Armor Class 15 (natural)
Hit Points 71 (11d8+22)
Speed 30 ft., burrow 15 ft., swim 15 ft.

16 (+3) 10 (+0) 14 (+2) 2 (-4) 12 (+1) 13 (+1)

Skills Athletics +5, Perception +3, Stealth +2, Survival +5
Damage Resistances cold
Damage Immunities poison
Senses darkvision 60 ft., passive Perception 13
Challenge 3 (700 XP)

Special Traits

  • Keen Smell. The jewel crab has advantage on Wisdom (Perception) checks that rely on smell.
  • Retraction. A jewel crab can pull its fleshy parts into its shell as a bonus action, allowing the jewel crab to use its shell as three-quarters cover. While retracted into its shell the jewel crab cannot move or attack. A jewel crab may reemerge from its shell by using its action.
  • Water Dependency. A jewel crab can survive out of the water for 1 hour per point of Constitution. After that, a jewel crab begins suffocating.


  • Multiattack. The jewel crab makes up to 2 claw attacks, 2 resin strand attacks, or any combination thereof.
  • Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage.
  • Resin Strand. Ranged Weapon Attack: +5 to hit, range 30 ft., one target. Hit: A Large or smaller creature hit must succeed on a DC 13 Dexterity saving throw or become grappled by the jewel crab (escape DC 15), with the grapple ending automatically if the target is moved further than 30 ft. away from the jewel crab. The jewel crab may, instead of moving, drag a grappled target 15 ft. towards it. A jewel crab can maintain a maximum of 2 targets grappled by resin strands at a given time. Any acid damage inflicted on a target grappled by the jewel crab dissolves the resin and ends the grapple.


Jewel crabs dwell within the coastal waters and spend much of their time wandering around the ocean floor in search for prey or things to decorate their shells, using strands of naturally produced adhesive resin. While jewel crabs are aquatic, they occasionally wander out of the water in search for decorations that wash up along the shores. They are usually not aggressive towards humanoids, but they will fight if they feel threatened or if they spot something interesting to decorate their shells in the possession of a humanoid. They are typically four or five feet tall and weigh about two hundred pounds, with their shells easily making up half of that weight. Jewel crabs typically live for about thirty years in the wild, with those being kept in captivity generally only living for about fifteen years.

Hermit Home. Jewel crabs have two large claws that are fairly precise despite their size and strength, eight segmented legs for movement, and a long spirally curved asymmetrical abdomen, which is soft and vulnerable to attack, unlike the shelled abdomens seen in other crustaceans. To protect their soft abdomen, they typically salvage an empty seashell from another creature, using it like armor and turning it into a comfortable place to hide by retreating inside of it, while using its claws as a door to block the entrance. A jewel crab’s body is pinkish in their immature state, shifting to dark blue in color as it matures, with glowing neon-blue accents. As they grow in size, they quickly become cramped inside their shell.

Whenever a jewel crab outgrows their shell, they are forced to find another. A jewel crab outside of its shell only has a natural AC of only 11.

Decorated Shell. Despite their biological need to change shells as they grow in size, they seem to be fairly picky about what they use; favoring the shells of sea snails, but scarcity can occasionally force them to use the shells of bivalves and scaphopods (or even hollow pieces of wood and stone) in a pinch. In particularly lean times where there are not many other options available, some naturalist philosophers have observed bullying other jewel crabs for their shells and it is not too uncommon to see two of them fighting over any appropriately sized shells with surprising fury should they find it at the same time. They seem to be quite vain about their shells, constantly decorating them with new bits of collected foliage, stones, and crystals.

No two shells are identical, but all are heavily decorated with chunks of crystal that give them their name.

Ironically, their apparent love for decorating their shells can also lead to problems, as their shells can grow too heavy under the load of so many decorations, which often leads them to abandoning their current shell for a new one.

Section 15: Copyright Notice

Sea Monsters (5E) © 2021, Legendary Games; Authors Michael Ritter, Michael “solomani” Mifsud, Robert J. Grady, Mark Hart, Jeff Ibach, Alex Riggs, Scott D. Young, Jeff Lee, Matt Kimmel, and Jason Nelson.

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