Tapeworms? Ticks? Fish lice? You name 'em, we’ve got 'em—and by “we,” I mean America. One of our country’s most underrated scientific treasures, the National Parasite Collection, is currently getting spruced up by zoologists at the Smithsonian.

The collection began in 1892, when researchers from the U.S. Department of Agriculture (USDA) started saving specimens for future reference. Almost from the beginning, the project was a collaboration between the USDA and the Smithsonian, with scientists at both institutions helping to collect, identify, and catalog the specimens that rolled in from around the country. The USDA even built a parasite library in Washington, D.C., where researchers could visit or even check out specimens to study.

Shortly after its inception, the parasite collection began to be shuttled back and forth between Smithsonian and USDA facilities, even as it continued to grow. As this timeline explains, the collection spent 45 years at USDA’s Beltsville research campus.

In 2014, the collection once again landed back at the Smithsonian. This latest hand-off was a bit more labor-intensive than previous exchanges, as the collection now includes around 20 million parasites preserved in bottles and jars and on microscope slides. Many of these, like the malaria parasite, are too small to see with the naked eye. Others are … a bit bigger, like the 30-foot tapeworms removed from the intestines of a dolphin.

Remarkably, as zoologist Anna Phillips told the Washington Post, the dolphin may not have even known the parasites were there. “The tapeworms were not a problem for it,” she said. “There were other things going on.”

Phillips and her colleague Bill Moser are spearheading the Smithsonian’s effort to take stock of what they’ve got. Although scientists from around the world have continued to call on the collection’s resources, the majority of specimens have spent the last century gathering dust in the basement of the Beltsville facility.

“We still are finding out what’s in here,” Phillips said. “It’s so much. We didn’t get a grasp on it when you’re moving massive amounts.”

Assessing the collection is going to be a huge project, but Phillips is glad to have the opportunity to spread awareness about our planet’s incredible parasitic diversity. “Most of the time, parasites aren’t causing major harm to their hosts,” she said. “They’re taking a little bit, what they need ... They can even be beautiful ... They have these really amazing morphological structures that are really pretty.”

[h/t Washington Post]