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Squidward J. Q. Tentacles, known as Teuthida, is a cannibal serial killer variant of his original counterpart and the main antagonist of Trident Terror.

When he and SpongeBob were kidnapped by Fryer and taken to the Chum Bucket, Plankton, with a decaying appearance, offered to taste a piece of chum to Squidward to survive. Squidward initially refused the chum, but after many weeks his body started decaying and dying due to starvation he decided to eat a small piece. This affected Squidward’s brain and made him develop a never-ending addiction to eat, assuming the alias of Teuthida.

More facts here: https://fridaynightfunking.fandom.com/wiki/Trident_Terror:_Vs._Teuthida#Teuthida