These disturbingly well-preserved human tapeworms:

Each of these jars contains a single tapeworm removed from the intestine of a human being, said Academy of Natural Sciences of Drexel University curator Ted Daeschler. These come from Joseph Leidy, who studied (among many other things) anatomy and parasitology way back in the 1800s. The unfortunate humans who these came from, though, are unknown. "I don't know the details about exactly sort of where he got his human pieces, you know," Daeshler told BuzzFeed Science. "You don't ask many questions about those days, right?"

Academy of Natural Sciences of Drexel University