Blood Barnacle

Tiny beast, unaligned

Armor Class 13 (natural armor)
Hit Points 25 (10d4)
Speed 10 ft, swim 30 ft.

2 (–4) 14 (+2) 10 (+0) 1 (–5) 12 (+1) 8 (–1)

Saving Throws Con +2
Damage Vulnerabilities fire
Damage Resistances necrotic
Condition Immunities prone
Senses blindsight 60 ft. (blind beyond this radius), passive Perception 11
Challenge 1/4 (50 XP)
Proficiency Bonus +2


  • Barnacle Shivers. Characterized by the inescapable cold—and subsequent shivering—that slowly pervades the victim’s body, barnacle shivers is a disease that infects creatures attacked by blood barnacles. Until the disease is cured, the infected creature can’t regain hp except by magical means, and its hp maximum decreases by 3 (1d6) for every 24 hours that elapse. This reduction lasts until the disease is cured. The creature dies if the disease reduces its hp maximum to 0. A Humanoid or Beast slain by this disease rises 24 hours later as a zombie. The zombie isn’t under the blood barnacle’s control, but it views the blood barnacle as an ally.
  • Blood Sense. The blood barnacle can pinpoint, by scent, the location of creatures that aren’t Constructs or Undead and that don’t have all of their hp within 60 feet of it and can sense the general direction of such creatures within 1 mile of it.
  • False Appearance. While the blood barnacle remains motionless, it is indistinguishable from a normal barnacle.


  • Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 5 (1d6 + 2) piercing damage, and the blood barnacle attaches to the target. While attached, the blood barnacle doesn’t attack. Instead, at the start of each of the blood barnacle’s turns, the target loses 5 (1d6 + 2) hp due to blood loss. The blood barnacle can detach itself by spending 5 feet of its movement. A creature, including the target, can take its action to detach the blood barnacle by succeeding on a DC 12 Strength check. When the blood barnacle is removed, the target takes 2 (1d4) piercing damage. If a creature ends its turn with a blood barnacle attached to it, that creature must succeed on a DC 12 Constitution saving throw or contract the barnacle shivers disease (see the Barnacle Shivers trait).


  • Host Defense. When a creature damages an attached blood barnacle with anything other than fire, the creature hosting the barnacle must succeed on a DC 12 Wisdom saving throw or use its reaction to protect the barnacle. The barnacle takes half the damage dealt to it, and the host takes the other half.


A cluster of tiny rock-like shells wait, attached to a floating barrel. Blood stains the water, and the red and black beaks open, revealing small tendrils that taste at the blood and pull the barnacles toward its source.

Found on ships, reefs, rocks, and old piers, these corrupted barnacles are by no means natural. Often gathered in groupings of five to ten, a blood barnacle infestation can prove to be a threat for any crew, particularly injured sea travelers seeking a good night’s rest.

Undead Origins. When coagulated blood drops off shambling undead zombies and into the sea, its necrotic blood may turn an ordinary barnacle into a blood barnacle. Large clusters of blood barnacles almost always indicate undead are nearby.

Prey on the Weak. Though a slightly deeper red than most red barnacles, the blood barnacle can often remain undetected among more benign barnacles. It can lie in wait for weeks or months for the perfect injured or heavily bleeding creature before latching onto its prey.

Resurrection. The remains of blood barnacles spawn more of their kind if not disposed of properly. Burning clusters of barnacles or blessing the area is the only way to ensure they don’t regrow.

Section 15: Copyright Notice

Tome of Beasts 3 © 2022 Open Design LLC; Authors: Eytan Bernstein, Celeste Conowitch, Benjamin L. Eastman, Robert Fairbanks, Scott Gable, Basheer Ghouse, Richard Green, Jeremy Hochhalter, Jeff Lee, Christopher Lockey, Sarah Madsen, Ben Mcfarland, Jonathan Miley, Kelly Pawlik, Sebastian Rombach, Chelsea Steverson, Brian Suskind, Mike Welham

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