Terraria Wiki

Miss the old Hydra Skin? Try out our Hydralize gadget! Visit the preferences page while logged in and turn on the gadget.


Terraria Wiki
Terraria Wiki
Desktop versionConsole versionMobile version
Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.
Master mode icon.png
Master Mode-Only Content: This information applies only to Master Mode and Master Mode worlds.
Brain in a Jar
  • Brain in a Jar item sprite
Stack digit 1.png
Use time20 (Very fast)
TooltipSummons a spider brain
'Pickled and shrunken, this brain can no longer hurt you.'
RarityRarity level: Fiery red
Research1 required
Grants Buff
BuffSpider BrainSpider Brain
Buff tooltipIt's crawling around . . . icky
Summons Pet
  • Spider Brain
    Spider Brain
Dropped by Dropped by
Master mode icon.png Master
Brain of CthulhuBrain of Cthulhu.pngBrain of Cthulhu125%

The Brain in a Jar is a pet item that can be dropped by Brain of Cthulhu in Master Mode with a 25*1/4 (25%) chance. It summons a miniature version of the Brain of Cthulhu, the Spider Brain.


  • The Spider Brain slightly resembles the Brain Suckler, which latches onto player's head.
    • Likewise, this pet and the object used to summon it may be a reference to a scene from the movie "The Iron Giant," where the main character is watching a horror movie in which a scientist knocks over a brain in a jar. Upon returning to his lab, the brain is no longer on the floor - two seconds later, the brain, now having developed four legs, two eyes and a mouth, leaps onto the scientists face.
    • That being said, it is also possible, but less likely, that this item is intended as a reference to the arachnotron from the DOOM franchise.
  • The item itself may be a reference to the brain in a vat, a scenario in thought experiments which involves placing a disembodied brain in a vat of life-sustaining liquid and connecting it to a supercomputer, allowing the brain to perceive itself to be experiencing reality as if it were in the outside world.