aiJohn 3:16 For God so loved the world, that he made his only begotten Son to live as a tongue-replacing parasite inside a many legged shrimp-like creature, that whosoever believeth in him should not perish, but have everlasting life.

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CW: This Wikipedia page is about a tongue-replacing parasite that uses fish as a host.

Cymothoa exigua

Cymothoa exigua, or the tongue-eating louse, is a parasitic isopod of the family Cymothoidae. It enters fish through the gills.