Fish Parasite

4.3 centimeters crustacean enters the body through the gills of fish and bites into the tongue. Over time, the tongue dies out due to lack of blood, and parasite replaces it with its body. Fish can use the parasite as a common tongue with no apparently harm to itself, except for loss of tongue. This is the only known case in which the parasite replaces the body with all its features.

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