A Rice University biologist found something a little horrifying in a fish’s mouth this week.

Kory Evans, an assistant professor in the Department of BioSciences at Rice, found a parasite that had made a meal of the fish’s tongue and effectively replaced it, CNN reports.

Evans studies evolutionary traits in fish, mainly their skulls. He’s currently scanning hundreds of species of wrasses and making models of their skeletons.

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On Monday, he saw one of the fish he was scanning had a full mouth. But instead of a tongue, he found a tongue-eating louse, an isopod parasite.

“It looked like it had some kind of insect in its mouth,” Evans said in an interview with Live Science. “Then I thought, wait a minute; this fish is an herbivore, it eats seaweed. So I pulled up the original scan, and lo and behold, it was a tongue-eating louse.”

Evans told CNN that the parasite enters through the fish’s gills and feeds on the tongue’s blood vessels until the tongue dies. The parasite then effectively replaces the fish’s tongue and can feed on the fish’s mucus for years.

It’s unusual to find a tongue-eating louse in a scan, and it’s unknown how common they are among fish. The biology community and other scientists were extremely excited by the find.

Evans told CNN he might research tongue-eating louses more when he’s done scanning wrasse skulls. But until then, he’ll continue cataloguing his research on Twitter under the hashtag #BackDatWrasseUp.