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Terraria Wiki
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Desktop/Console/Mobile/Switch-Only Content: This information applies only to the Desktop, Console, Mobile, and Switch 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
Obtained from Obtained from
Master mode icon.png Master
Brain of CthulhuBrain of Cthulhu (First Phase).gifBrain of Cthulhu125%

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


  • Desktop 1.4.3: Changed buff tooltip from "It's crawling around . . . icky" to "It's crawling around... icky".